Analysis
Once again, this is predicated on a Democratic blow-out, which I think will once again happen this cycle. Too many things are going against the Republicans, and I think Obama will raise turnout somewhat for Democrats and liberals while McCain will lower turnout somewhat for Republicans and conservatives.
I think that Virginia and New Hampshire are near-locks for the Democrats, although I don't want to entirely count out an incumbent so I'll make New Hampshire only a "lean."
Democrats have a clear advantage in Colorado and New Mexico, with a stronger, better funded candidate in New Mexico facing a conservative who just barely won a bitter primary. In Colorado, the Democratic candidate again has more money, but also has less scandals to deal with and is probably slightly better known. In both cases, I think the states are trending Democratic.
Oregon and Minnesota don't have the best Democratic challengers, but both will probably capitalize on Democratic turnout and Republican unpopularity.
If Ted Stevens is the Republican candidate, and I think he will be, Mark Begich will probably win. Even if Stevens loses, none of his challengers look particularly strong, and will have won a most likely divisive primary and will have little time to prepare for the general election. Either way, I think Begich has an advantage, and is a good candidate.
Poll numbers look great in Mississippi and North Carolina, and we have a great challenger in Maine (although the polls look bad). Wicker really should win in Mississippi but between the polls and Childers's win in the special election (which, similar to the upcoming Mississippi senate election, had no party on it) I'm going to call that race a toss-up/leans Republican.
I expect one out of those three races will be won by the Democrats, while one out of the seven races I called for the Democrats will be won by a Republican.
I could also see the Democrats giving a good run at seats in Kentucky, Kansas, and Texas. I think the challengers in Nebraska and Oklahoma are too liberal (Nebraska in particular is a lost cause imo, though I could see a crazy Inhofe making Oklahoma competitive), and I've seen nothing to indicate any other race will be competitive, although Tennessee could possibly elect a Democrat under the right circumstances (as shown by Harold Ford's close run a year ago).
So I see a net gain of seven seats (leaving the Democrats at 58 seats...I really don't see Lieberman switching parties), which should allow President Obama plenty of leeway in his first two years.