From Newsweek, by Nate Silver. He agrees with me that wins in Pennsylvania and Virginia for Obama would make this an early night:
Virginia, for my money, is the most important state in this election. If John McCain loses it, his path to victory is exceptionally narrow—he would need to pull out an upset in Pennsylvania, while holding on to Florida and Ohio, and avoiding a sweep out West.
He also reiterates here that Colorado is the other big one right around the tipping point, but since it’s out west, its brothers VA and PA will be much more likely to get the drama:
Colorado, meanwhile, is the last of what I’d characterize as this year’s “Big Three” states (the others are Pennsylvania and Virginia). If Pennsylvania and Virginia have split their votes (and Obama hasn’t picked up Ohio or Florida), then Obama probably wins if he wins Colorado, and loses if he doesn’t.