How would this strike you as an example of the Law of Unintended Consequences at work?
"If he switches parties, he delivers control of the Senate to the GOP for the next two years, and makes Dick Cheney a very busy man. It forces the Democrats to carefully consider Lieberman when determining policy, especially on the war. It might force the Democrats to escalate efforts to get a Republican to cross the aisle, which would neutralize Lieberman."
Joe Lieberman is going to be a VERY important man when the new senate reconvenes in January.