CBS polling suggests  Obama won among undecides, and won big:
CBS News and Knowledge Networks conducted a nationally representative poll of approximately 500 uncommitted voters reacting to the debate in the minutes after it happened.
These figures are still preliminary and could change as more respondents complete the survey. But here's what we have so far:
Forty percent of uncommitted voters who watched the debate tonight thought Barack Obama was the winner. Twenty-two percent thought John McCain won. Thirty-eight percent saw it as a draw.
Of course, as we learned from 2000, the media have a few days to change viewers' minds about what they saw.
Let's hope this time they focus on fact-checking the candidates' claims rather than engaging in theater criticism.
UPDATE: Politico's Roger Simon isn't wasting any time  trying to change voters' minds.