John Sides writes at The Monkey Cage that polling finds that how Americans felt about Romney, particularly independent voters, became more positive. He says there are six attributes that shifted significantly in favor of Romney after the debate.
Ultimately, the question is whether these trends persist. The apparent size of this debate bump is certainly larger than my back-of-the-envelope prediction. It is more in line with a caveat I introduced in that post, and that Matt Dickinson noted as well: the bump seems to have brought the race closer to where it "should have been" based on the underlying fundamentals. But, as Ezra Klein wrote, the real question is the outcome of debate season as a whole. We'll know soon enough.