I just got done watching the first presidential debate. Overall, I thought both candidates held their ground but that McCain won by a small margin. McCain was on the offensive far more, seemed to have a greater command of the facts, and was able to demonstrate how much experience he has relative to Obama. (Something that I think will come back to haunt Palin in comparison and something the Obama campaign is likely to latch onto.) It didn't help Obama to keep repeating the phrase "John is right."
Overall, I think this debate may give a small bump to McCain, but nothing too significant. What will be particularly interesting is to see the Biden-Palin debate next Thursday.