Barring any unexpected developments, I'm betting McCain is going to win the election with somewhere between 270 and 290 electoral votes.
The surge in new voter registration will be largely countered in battleground states by the usual vote-suppression methods -- long lines due to inadequate provision of voting machines in dense urban precincts, misinformation and intimidation to prevent people from showing up to vote at all, systematic purges of the voter rolls, et cetera.
Obama may very well still win the popular vote, since many people in solid blue and red states are going to turn out to cast a historic ballot for the first black President who wouldn't otherwise bother to vote, knowing their state's outcome was basically decided already. Still, I'll be shocked if this is enough to overcome the dirty tricks that they're up against in the states where it counts.
As has been the case every two years since 2000, Dems will briefly show an interest in theft-proofing the electoral system in the two or three months that follow. Reeps will gloat and strut and tell America to quit whining, the people have spoken. Congress will slap a half-assed band-aid on the problem, and state officials will immediately start looking for ways to delay, circumvent, or counteract any reforms that actually get passed.
Everyone will then promptly forget about the problem until November 4, 2010.