Obama's appeal and conciliatory style has been known from some time.  Take, for instance, this in-depth article from The New Yorker.

Obama’s voting record is one of the most liberal in the Senate, but he has always appealed to Republicans, perhaps because he speaks about liberal goals in conservative language. When he talks about poverty, he tends not to talk about gorging plutocrats and unjust tax breaks; he says that we are our brother’s keeper, that caring for the poor is one of our traditions. Asked whether he has changed his mind about anything in the past twenty years, he says, "I’m probably more humble now about the speed with which government programs can solve every problem. For example, I think the impact of parents and communities is at least as significant as the amount of money that’s put into education." Obama encourages his crossover appeal. He doesn’t often criticize the Bush Administration directly; in New Hampshire recently, he told his audience, "I’m a Democrat. I’m considered a progressive Democrat. But if a Republican or a Conservative or a libertarian or a free-marketer has a better idea, I am happy to steal ideas from anybody and in that sense I’m agnostic." "The number of conservatives who’ve called me—roommates of mine, relatives who are Republicans—who’ve said, ‘He’s the one Democrat I could support, not because he agrees with me, because he doesn’t, but because I at least think he’ll take my point of view into account,’ " Michael Froman, a law-school friend who worked in the Clinton Administration and is now involved in Obama’s campaign, says. "That’s a big thing, mainstream Americans feeling like Northeast liberals look down on them."

Respect for and a willingness to listen to those with whom he disagrees--even Republicans and conservatives.  This trait gives him great crossover appeal, without sacrificing any commitment to progressive values and goals.

This is a trait he has shown even before entering politics.

Barack is a deeply committed liberal, and I am a proud conservative. Even so, he possesses five qualities that are genuinely praiseworthy -- political ideology aside:

He listens. Certainly, Barack is a liberal’s liberal, and his leadership of The Harvard Law Review in many ways reflected that fact. But unlike many of his left-wing compatriots, he treated his ideological adversaries with respect on a personal level. Indeed, he always offered the small conservative contingent on the Review a hearing, even though his decision-making consistently showed that he hadn’t ultimately been influenced by their arguments.

More from arch-Republican Dean Barnett:

IN MY PREVIOUS PROFESSIONAL life, I had reason to be in contact with dozens of Barack Obama's classmates at Harvard Law School. When he entered the presidential race, I dusted off my Rolodex and began making some calls to get the off-the-record skinny on the Democrats' potential savior.

The results surprised me. Regardless of his classmates' politics, they all said pretty much the same thing. They adored him. The only thing that varied was the intensity with which they adored him. Some spoke like they were eager to bear his children. And those were the guys. Others merely professed a profound fondness and respect for their former classmate.

Even more interesting was what wasn't said. In dozens of conversations, not a single person said anything negative about him, and some were hardly the senator's political fellow travelers. Also noteworthy is that virtually everyone seemed to know Obama. Usually people who have such a high profile on law school campuses have their detractors. Obama apparently didn't.

A great example of Obama's crossover appeal is found in this story from Iowa.

Hedgecoth estimates 15 percent of the people walking into and volunteering at the Linn County for Obama office are Republicans or former Republicans. Electing someone who can represent and find support on both sides of the political spectrum, he said, should go a long way to ending "the political gridlock" of recent years.

"With all the challenges our country faces, we cannot elect a president who will go to Washington and just get bogged down by the same partisan gridlock," said Brett Blix, a 30-year-old Iraq war veteran from Northwood who switched his party registration to caucus for Obama. "That's why I'm supporting Senator Obama even though I'm a Republican. He's the only candidate in either party with a record of bringing Republicans and Democrats together to solve problems, and he will always tell you where he stands even when you disagree. There are thousands of disaffected Republicans like me who are disappointed by President Bush and the Republican presidential candidates who would consider voting for a Democrat who can bring about change we can believe in."

This basic respect for others, regardlesss of ideology, allows Obama to get away with unambiguous assertions of progressivism.

Obama has begun to embrace positions that a generation of Democrats have been advised to avoid. The political "textbook" calls for a relatively inexperienced first-term senator to run hawkishly. Obama, whom Clinton criticized when he said that he would negotiate directly and without preconditions with America’s adversaries, now makes it a point to mention that he would sit down with Mahmoud Ahmadinejad, Iran’s President. On the question of torture, which Obama unequivocally opposes, the political temptation is to signal a willingness to show no mercy to our worst enemies, in much the way that Governor Bill Clinton, in his first campaign for President, returned to Arkansas for the execution of Rickey Ray Rector, a mentally disabled death-row inmate. On the increasingly perilous subject of illegal immigration, Obama favors issuing state driver’s licenses to undocumented workers, and tells voters, "We are not going to send twelve million people back home." When discussing his energy plan, Obama says, "You can’t deal with global warming without, at least, on the front end, initially, seeing probably some spike in electricity prices," and on Social Security he proposes what is, in effect, a large tax hike. These issues all have one thing in common: Hillary Clinton’s positions are artfully vague—aimed at surviving the general election—while Obama insists that it is more important to be forthcoming.

Respect for the views of others--even Republicans--gives him the liberty of being perfectly clear about where he stands on issues.  That, in turn, inspires respect.  

What was notable about Obama’s speech at the dinner—one of his finest and most passionate—was not just the roaring choreography from his red-clad supporters but the way that, at 11:30 P.M., he galvanized the entire auditorium, with a succinct description of the difference between his campaign and Clinton’s: "If we are really serious about winning this election, Democrats, we can’t live in fear of losing it." Even many of Clinton’s troops could be seen beating yellow thunder sticks together in appreciation. Obama seemed to be making an argument about the connection between boldness and electability. With Hillary Clinton, he suggested, there is an inverse relationship between the two: she is so polarizing that she is forced to be a milquetoast candidate in order to become an electable one.

Interview with Ryan Lizza in The New Yorker.

Indeed.  When the issue was drivers licenses for undocumented workers, who wound up getting attacked--the person who dodged the issue or the candidate who unambiguously took the unpopular one (according to polls)?  

Obama will not be a waffler.  This is smart on a couple of levels.  First, waffling is bad politics.

Why? Because the Democrats had decided to run by being the anti-George Bush... and count on the anger and frustration of the electorate to solidify a majority. Any position or point of view risked alienating someone, and so it was to be avoided.

So deep was the denial about the Democratic party's fatal compromise - that my film "Inside The Bubble" was deemed shocking and unwatchable by those few Democrats that saw one of the few closes screenings we held before I put the project in my desk drawer.

But in the past few weeks - something happened.

My phone started ringing. And not just from friends and neighbors. Some of my friends rather high up in the Democratic party, and even a few of the well known faces from the Kerry campaign.

They were scared. They had a desperate feeling that it was groundhog day. That increasing the Clinton campaign had shifted from a candidacy of ideas to a platform of platitudes. It came home to roost when Hilary did what is fast becoming her 'double flip flop' - at first supporting drivers licenses for illegal immigrants, then didn't, and then wasn't sure.

This is doubly so when we face a change election.  As our very own Bob Johnson discussed:

Is Clinton's DLC centrism enough change? Current polling of independents indicate it is not.

The worrisome point of all this for Democrats is that Hillary may win the battle, but Democrats could lose the war come November 2008.

If nothing else, this election may put a stake through the heart of the tired DLC election model. Al From and his DLC acolytes are still clinging to a strategy that may have been valid in 1992, post-Reagan, but has grown increasingly irrelevant.

Voters and electoral politics are not static entities. (How else to explain the continuum from FDR to Reagan?) But Clinton and the DLC act like it's still 1992... Because, after all, DLC types forever point to Bill Clinton as their greatest success, not unlike the 45-year-old suburban male in a John Cheever novel who bores friends and neighbors by endlessly recounting the glories of his high school sports exploits.

We as Democrats may learn a very painful lesson come November 2008: Hillary Clinton's centrism is, indeed, a model that should have been retired long ago.

Clarity may be good politics, but it is even better policy.  From the Lizza article:

But Obama also wants to make a more substantive point, showing that an emphasis on truthtelling during a campaign can in the long run be better politics. "What happens when we finesse the big issues during the campaign is we never build a mandate," he told me. "Because the American people start thinking, You know what, these problems are pretty easy to solve. Then we start to actually try to move something through, and then—oops! It turns out we might have to deal with the tax code or there might be a cost associated with capping energy costs. And people aren’t ready for it. Republicans exploit the gap between people’s expectations during a campaign and what actually has to get done. And that’s why we keep on putting things off. So if you believe that these are problems that are incremental in nature, that really you just have to do a tweak here and a tweak there, and that our big problem has been that George Bush has just been a poor manager of government, then I think that Hillary’s arguments are persuasive."

Obama is not the most liberal candidate in the race, so he’s not defining his boldness strictly in ideological terms but, rather, as a sort of anti-politics that prizes truthtelling above calculation. When I asked him about this new tack, he seemed supremely confident. "I’ve been an observer of politics for two and a half decades, and what I’ve seen is that Democrats have not been able to move their agenda through Washington," he said. "They have not been able to get the American people to embrace their domestic agenda, and they have been constantly on the defensive when it comes to their foreign-policy agenda. And it seems to me that, you know, if you’re not getting the outcomes you want, you might want to try something different."

And Obama is articulating the rationale for his candidacy along these lines.

And that is why the same old Washington textbook campaigns just won’t do in this election.  That’s why not answering questions ‘cause we are afraid our answers won’t be popular just won’t do. That’s why telling the American people what we think they want to hear instead of telling the American people what they need to hear just won’t do. Triangulating and poll-driven positions because we’re worried about what Mitt or Rudy might say about us just won’t do.  If we are really serious about winning this election Democrats, we can’t live in fear of losing it.

This party – the party of Jefferson and Jackson; of Roosevelt and Kennedy – has always made the biggest difference in the lives of the American people when we led, not by polls, but by principle; not by calculation, but by conviction; when we summoned the entire nation to a common purpose – a higher purpose.  And I run for the Presidency of the United States of America because that’s the party America needs us to be right now.

When I am this party’s nominee, my opponent will not be able to say that I voted for the war in Iraq; or that I gave George Bush the benefit of the doubt on Iran; or that I supported Bush-Cheney policies of not talking to leaders that we don’t like.  And he will not be able to say that I wavered on something as fundamental as whether or not it is ok for America to torture – because it is never ok.  That’s why I am in it.

And if those Republicans come at me with the same fear-mongering and swift-boating that they usually do, then I will take them head on.  Because I believe the American people are tired of fear and tired of distractions and tired of diversions. We can make this election not about fear, but about the future.  And that won’t just be a Democratic victory; that will be an American victory.

Because I will never forget that the only reason that I’m standing here today is because somebody, somewhere stood up for me when it was risky.  Stood up when it was hard.  Stood up when it wasn’t popular.  And because that somebody stood up, a few more stood up.  And then a few thousand stood up.  And then a few million stood up.  And standing up, with courage and clear purpose, they somehow managed to change the world.

Obama is thus challenging two myths that have poisoned our discourse:

1.  That respect for the other side is bad and a sign of weakness, and that us vs. themism is the only viable approach to modern electoral politics;  and

2.  That we need to downplay our goals and err on the side of caution when articulating the rationale for our party and our candidate.

Both of these myths have played into the hands of the Republicans--the former by creating a cynical and increasingly selfish electorate, and the latter by frustrating the progressive agenda and causing us to play defense instead of moving forward.

Postscript:  Obama's approach is not without its pitfalls.  When one tries to show respect for everyone despite disagreement, that respect can take the form of a symbolic quiescence in the very wrongheaded and awful ideas with which he disagrees.  And, Obama got burned by this by trying to show respect to culturally conservative and too frequently homophobic African-Americans while advocating LGBT-friendly policies.  Thanks to a series of campaign errors, he wound up having a person using Obama's stage to spread a message that Obama himself rejects.  He (and especially his campaign) provided fodder for any number of charges, from ham-handed incompetence to cynical and even malicious pandering to bigotry.  Showing respect to the person without showing respect or approval for the ideas is a fine wire to walk, and he didn't pull it off.  I myself think that he should have decided to show less 'respect' for people like McClurkin--especially in the aftermath of McClurkin's incredibly awful tirade.  But, the grim reality of political campaigns is that one must not turn yesterday's mistakes into today's stumbling blocks.  He has said some encouraging things since then, but not enough to satisfy me completely.  But, no candidate and certainly no candidacy is perfect.