There are still two undecided Senate seats from election 2008: Georgia and Minnesota. There was a run-off today in Georgia between Saxby Chambliss, the incumbent Republican and Jim Martin, the challenging Democrat. In the general election, Libertarian Allen Buckley kept either candidate from getting 50%. In Georgia, that means a run-off vote between the top two vote getters. Turnout is unpredictable in run off elections, so it’s hard telling who will win; though Chambliss has to be regarded as the favorite.
Meanwhile, a recount in Minnesota between incumbent Republican Norm Coleman and Al Franken, the challenging Democrat has the gap between the two down to 13 votes by some estimates.
If the Democrats were to pull off both of those upsets — not especially likely — the Republicans would have only 40 votes, not enough to mount a filibuster. Of course, Joe Lieberman is one of the remaining 60 votes, so he could probably be counted upon to stab the Democrats in the back at opportune times, knowing that a Sternly Worded Letter ™ from Harry Reed is about the worst he could expect to suffer in response.