From the LA Times:
Bottom-line: barring a major reversal of political trends, Democrats not only are poised to build on the narrow Senate majority they surprisingly captured in the 2006 election, they could substantially expand it.
They're going to need a substantial expansion. It takes 60 votes in the Senate to get anything done, due to procedural rules, and a 51-member majority, when one of those members is Joe Lieberman, just isn't going to cut it. The vulnerable seats:
That's seven states. Then you've got a bunch where a Republican incumbent is kinda sorta vulnerable: New Mexico, Alaska, and Kentucky. No promises there, but still: looking good, folks.