Matt Y. gives us a taste of when we'll know Obama's won this thing.
Virginia and Indiana close at 7PM Eastern, Ohio closes at 7:30PM Eastern (the portions of Indiana in Eastern Time actually close at 6PM) and then Florida closes at 8PM Eastern with the vast majority of the state (the non-panhandle part) closing at 7PM Eastern. In practice, McCain needs to win all four of those states to have a shot at the election, and he’s currently behind in three of them. It’d still take a while before anyone concedes anything, and political junkies will want to see Senate outcomes in Alaska and Oregon, but it’s very possible that the country will basically know the outcome of the presidential election pretty early.In the worst case scenario that McCain does manage to win all four—and North Carolina, and Missouri, and Georgia and West Virginia, and all the other states that currently look to be in play—it'll then come down to Colorado, where the polls close at 9 PM EST. If Obama wins there and in New Mexico, he still wins, even if he loses everywhere else.
RCP has a six-point Obama advantage in Colorado.