The pundits will probably score this as either a tie or somewhat of a victory for Palin, because her expectations coming in were literally akin to expectations of a vegetarian in the July 4th hot dog-eating contest. But in my own partisan view, I think Biden came across as the more plausible president by far.
Biden really came alive in the foreign policy section, and I think it was also clear that as the debate went on and on, Palin seemed to shamelessly revert back to folksy catchphrases and stupid talking points about "Wasilla Main Street" and the like.
Again, if you thought Palin was going to get up there and drool all over herself, you were probably disappointed. But Biden - and it should come as no surprise - really knows his stuff. And it showed. He can talk about substantive issues - particularly foreign policy - like no one else can. Biden clearly came across as more prepared and more knowledgeable, while Palin probably did indeed come across as "one of us." And people might go for that. But in these tough, tough times, people will go for Biden too.
All in all, probably a draw. And I doubt it will have much effect. The strong Obama momentum in the polls might be stalled a bit because of this, but I suspect we'll all have forgotten about this by the next presidential debate next Tuesday.