Obama will win 353 electoral votes. He will win, going from states I'm most confident about to states I'm least (Things in bold are things I looked up after finishing the post; the rest was from memory, a sign that I've spent way too much time with this stuff):
All the Kerry states minus Pennsylvania (231 EVs)
Iowa (7 EVs)
New Mexico (5 EVs)
Pennsylvania (21 EVs)
Colorado (9 EVs)
Virginia (13 EVs)
Nevada (5 EVs)
Ohio (20 EVs)
Florida (27 EVs)
North Carolina (15 EVs)
It's also possible, but unlikely (from least to most unlikely), that he'll win Missouri (11), Indiana (11), Nebraska's 2nd District (1), North Dakota (3), Montana (3), Georgia (15), Arizona (10), West Virginia (5), Louisiana (9) South Dakota (3), Arkansas (6), and South Carolina (8). Which gives Obama an absolute ceiling of 438.
That leaves Alabama (9), Mississippi (6), Texas (34), Oklahoma (7), Nebraska's other votes (4), Kansas (6), Wyoming (3), Utah (5), Idaho (4), Alaska (3), Kentucky (8), and Tennessee (11) for McCain's safe states, totaling 100 EVs.
(Note: Some bolds there. In my defense, these states are perfectly safe for McCain and therefore boring.)
The Democrats will pick up 8 Senate seats, leaving them, sadly, one seat short of 60, again starting with the ones I'm most confident about:
There are 39 Democratic Senators not up for re-election; Obama will be replaced with another Democrat
All 12 incumbent Democrats will win, including Biden, who will also be replaced with another Democrat, possibly his son, Beau.
Udall in New Mexico over Pearce
Udall in Colorado over Schaffer
Warner in Virginia over Gilmore
Shaheen in New Hampshire over Sununu
Begich in Alaska over Stevens
Hagan in North Carolina over Dole
Merkley (only bold for spelling) in Oregon over Smith
Franken in Minnesota over Coleman
I feel very, VERY confident about the first six, pretty darn good about Merkley, and better than 50/50 about Franken. They also have an outside chance at beating Chambliss in Georgia, McConnell in Kentucky and Wicker in Mississippi. Any one, along with winning the 8 above that they're supposed to win, would mean 60. Depends on African-American turnout in these red states.
I haven't really read anything about governorships or House races, so look elsewhere for predictions on those races.
So tune in tomorrow and see how I did. You better believe there's going to be a live blog.