Gallup poll confirms that Obama absolutely crushed McCain in the 2nd debate, 56-23
This poll is notable for several reasons. It wasn't a snap poll conducted immediately after the debate - Gallup waited 24 hours to call people, so folks had a chance to think about it, and discuss with friends and family, and not just give a quick emotional reaction. The poll's also based on a fairly large sample size, over 1000 calls and over 700 who actually watched the debate.
Gallup poll on the 2nd debate