A few thoughts on the debate...
It was more or less a tie. Obama and McCain both held their own; neither blew the other away; neither said anything egregiously stupid.
Since Obama is ahead, and since foreign policy is supposed to be McCain's strong suit, Obama probably wins by tying.
It remains to be seen whether undecideds/independents share my view that McCain often came across as an angry codger more intent on attacking Obama than answering questions, while Obama came across as calm, rational, and much more likable. If that's the case, then Obama "won."
The "winner" and "loser" ultimately come down to media spin (e.g., Gore blowing Bush away on substance in 2000, but "losing" in the media because he "sighed too much"), so who knows what the final perception will be.