Silver rounds up the insta-polls:
A CNN poll of debate-watchers found Mr. Romney very clearly ahead, with 67 percent of registered voters saying he won the debate, against just 25 percent for President Obama. A CBS News poll of undecided voters who watched the debate found 46 percent siding with Mr. Romney, 22 percent for Mr. Obama and 32 percent saying it was a tie.
He thinks "it seems likely that Mr. Romney will make at least some gains in head-to-head polls after the debate, and entirely plausible that they will be toward the high end of the historical range, in which polls moved by about three percentage points toward the candidate who was thought to have the stronger debate." Harry Enten's view of the race:
At this point … my belief is that we'll return somewhere close to where we were before the conventions: a small Obama lead of about 1.5 points. There just aren't that many minds that Romney can change at this point. Democrats can also take heart that Republican excitement eventually rebounded a few weeks following President Bush's 2004 debate debacle. Still, my confidence in an Obama victory is at least somewhat shaken right now. Obama's lead is probably not big enough for him to play the super-cautious game he did on Wednesday.
Nate Cohn will be watching the polls over the next week:
While the post-debate polls might slightly exaggerate Romney’s standing, the polls over the next week or so are still quite important. The leader in the post-debate polls has won the presidency in every election with a presidential debate (caveat about the popular vote-electoral college split in 2000) and shifts from this point on are generally relatively modest. This doesn’t mean that the candidate’s couldn’t overcome a small deficit, but, from this point, the chances of a comeback get slimmer and slimmer with every passing day. Along those same lines, Romney's chances essentially dwindle to risk of a systemic polling failure, exogenous game changing event, or something historic if Obama maintains a modest lead in next week's polls.
(Chart above from Intrade, where Obama's chances of winning dropped by several points during and after the debate.)