I thought the first debate was a toss up. Obama clearly won this one IMO. His "home run", so to speak, was on the question about laying out the Obama doctrine and McCain doctrine on how they'd use the military to intervene in situations like the Congo, Rwanda, etc. that aren't a clear threat to the US. He knocked that out of the park, and the +/- trendlines among undecided Ohio voters that CNNHD displayed during the debate showed the undecideds ate it up as well.
Indeed, all night those undecides were very high on Obama's responses, and often neutral on McCain's, or at best less positive.
With current polling, this debate only helps Obama. McCain needed a clear win, and he clearly didn't achieve that.