My guess is that Obama is the slight favorite to win all four (well, not Alaska), but in order from most certain to least certain...
1. Indiana. All those volunteers in Gary may have made the difference.
2. North Carolina. It's clooooooose but Obama has a small lead and there's just not much vote left out there to count.
3. Montana. The Obama campaign was vewwy vewwy quietly feeling optimistic about this state, and holding onto a small lead with about half of the vote in.
4. Missouri. Looks like Obama's got plenty of votes left in St. Louis, but I haven't done the math.