I don't see how the Democrats don't gain at least one seat. The only seat that the Republicans have a chance at is Louisiana and even there they are having trouble finding a candidate.
While it seems likely that Democrats will gain seats in 2008, it is in no way "certain." No net change remains a strong possibility if the GOP and Dems trade Colorado for Louisiana (very possible), and there's a slight, though statistically significant chance that Republicans hold their current seats while picking up Louisiana, for a net gain of 1. South Dakota could similarly be a GOP opportunity, provided Governor Rounds runs or Johnson retires. (Rounds is being heavily recruited, and has made trips to the White House to discuss a possible bid.)
Democrats are in terrific shape, but in politics, nothing is guaranteed.
As usual, people forget Mississippi, but if Cochran were to retire (good chance of that), Mike Moore would have a legitimate shot of picking up the open seat.
Well, you know, Mississippi is forgettable because you greatly overestimating how "legitimate" that shot is in the ever-more-red south.
As I've said before, Oklahoma could be a dark-horse race for the Democrats. We have the talent, and the Oklahoma Democratic Party is strong enough to put up a very viable candidate in 2008 against Jim Inhofe and in 2010 against Tom Coburn as well as retaining the Governor's Mansion.
I give Oklahoma a 35-45% chance of switching right now.
Those are awful optimistic odds considering that Democrats don't even have a candidate there yet!
Nebraska-Dependant on whether or not Hagel will run. If he runs, Strong GOP. If he doesn't, Tossup.
The idea that Hagel would not be safe if he ran is funny, but the idea that Nebraska would be a toss-up if he didn't is funnier still. If only Nebraska thought as fondly of Scott Kleeb as the kids at DailyKos do!