I only saw the end of the "debate" (these things are more spectacles of endurance than arguments). It all sounded very shrill and was mostly an exchange of talking points and constituent button-pressing. However, people were glued to the whole show here in little old New York. On my way back from teaching, the little bar around the corner from us was packed with people watching it. I stopped by the neighborhood pizza joint for a slice of pepperoni and saw the kitchen help in the back watching it in Spanish. So far today, from what I can glean from the news, not too many minds were changed. The people who were predisposed to support Sarah Palin loved her performance, and the people inclined to vote for Joe Biden were satisfied with his. There seems to have been little to no movement in the polls so far.
My favorite essay on the whole Sarah Palin phenomenon so far is one written today by Digby at her blog, Hullabaloo. She describes Palin as a female clone of George W. Bush; arrogant, incurious, petulant, and dumb, a "faux populist." If McCain wins, and she becomes a kind of Cheney eminence grise, then it really will be 4 more years of the Same Old Shit.