I thought Obama got in some good punches with lines like "you pretend like the Iraq war started in 2007, it started in 2003". I also think he came across visually very well. He kept his cool, smiled, and was clear. A much better performance than Kerry 4 years ago. I think everyone also has to remember that this topic is supposed to be McCain's strong point(foreign policy), and so since he didn't hit anything out of the park, Obama won.
Also, I believe that when the news starts back up again on Monday, this first debate will remain in the news cycle up until Tuesday night. Then the talk turns to the Vice President Debate. That's when the fun will begin. I expect the national polls to go back to almost a tie up until about Wednesday, and then the polls will swing back into Obama's court.