7PM: VA & GA
Two solid red states. This will be a big test for Obama. The big question here is if we can trust the polling & turnout expectations that are causing traditionally red states to go blue. If McCain were to win either of these states by comfortable margins it might be the first sign of trouble for Obama. If Obama wins VA and GA is too close to call it's very good news for him.
7:30: OH, NC
First big traditional battleground state. The big thing to look for here is if the polls actually close at 7:30 or not. If they are held open later it would suggest huge voter turnout which would undoubtably help Obama. I expect McCain to win OH however, again, it should not be by a huge margin. If the margin is big enough for the networks to call OH before 9PM we might be looking at a very close election.
8PM: PA, FL, NH, IN, MO
This is the big test for McCain. PA, FL, IN, MO are must-wins for him. If these states remain too close to call until 9:30PM or later it would be a sign McCain is in big trouble. It's very doubtful he could win all these battlegrounds by razor thin margins. If he is going to make a stand and win --he will probably do so with comfortable margins in at least FL, IN and MO. Perhaps the most important state here is MO. Even if McCain wins PA he still needs MO.
9PM: AZ, CO, NM
Important but probably not as much so as we thought 3 months ago. The election will be largely decided by the time these states are called one way or another. The 9PM mark is more important simply because we'll be getting states closing at 8PM getting called by the networks.
So as I've been saying for the last 2 weeks... PA is the state to watch. Obama can win without PA but it's certainly more difficult. McCain simply cannot win without PA.