I didn't see this diaried already, so here you go. Survey USA has polled Iowa and found that Obama leads McCain 47% to 38%. Looking at the crosstabs, this looks somewhat better than the Ohio poll last week did, since this has Obama winning independents 48% to 33%.
However, this poll also has a big percentage of Democrats in the sample - the numbers are 45% Democrats, 28% Republicans, and 24% independents. The CNN Iowa exit poll for 2004 put the voting numbers at 34% Democrats, 36% Republicans, and 30% independents.
So either we've seen a big shift in party ID in Iowa (not impossible, the entire country is having buyer's remorse over the Republicans, and Iowa more so than most states, it seems), or the poll is suspect. Take your pick.
They also polled various VP combinations, as they've been doing in other states. Since Edwards has consistently polled as the strongest pick for Obama, and Huckabee and Romney have consistently polled as the strongest picks for McCain, I think this is probably mostly just name recognition at this point. However, it's worth noting that Obama/Edwards beats McCain/Pawlenty by a ludicrous 26 percentage points. The best combination for McCain (McCain/Huckabee) beats the worst combination for Obama (Obama/Rendell) by only 8. Make of that what you will.
The poll is here.