Looking at the contested primary results so far, it seems to me that something interesting is happening in both parties. The barbarians are storming the gates.
Up to now, the criticism that the Netroots and Tea Partiers really hadn’t accomplished much when opposed by traditional interests was not entirely unfair. Sure the Netroots won the primary in CT, and but they were unable to defeat Joe in the general. Obama's triumph over Hillary was the start of something different.
A start that has only grown and spread to the other side. In both parties the insurgent candidacies are winning. If Blanche Lincoln loses the runoff, it will be two Senators taken out by the insurgents. Charlie Crist had to leave the GOP (a sitting Gov for corn sake!)
This represents, I think, the profound change that the internet is working on politics. In the days before the internet, some kind of large organization like a union, or a political party, or a corporation, was needed to organize people into contributors, concentrate money around a candidate, and establish a campaign.
With the rise of the internet, politics has moved downstream to the end user. Anyone can raise money, attract a following, establish a group of supporters/volunteers.
This is good, in that it shakes up the vested interests.
This is bad, in that the vested interests tended to temper who was selected to run for high office. True believers with an emotional appeal of the moment, are now much more likely to be nominated, and therefore elected.
I think the internet is going to push politics even further in the directions started by earlier electronic media – away from the middle and towards the ends of the spectrum. This is the dark side of the network effects.
Some may consider this a good thing. I'm not so sure. The genius and curse of the American system is checks and balances. They inhibit government from swinging in wild extremes. Of course it also sometimes inhibits effective action in the face of a crisis, see for example, global warming. This genius is undermined, if at every level of government, people from the edges of the spectrum inhabit most of the positions of power.
Admittedly, this sounds a little alarmist, and it is early in the new history of politics to say anything definitive. Still, it is interesting to think that the greater access to politics provided by the internet, also leads to greater extremes.