I haven't commented extensively on L'Affire Lieberman, in part because I personally feel somewhat agnostic about it and in part because I think the writing has been on the wall for some time that Democrats would decide to keep him in their caucus and let him retain his chairmanship of the Homeland Security Committee.
One thing's for certain, though: when a vote that looked as though it was going to be fairly close originally instead passed the caucus 42-13, something happened to whip that result into shape, and that something was Barack Obama. True the caucus might have voted to retain Lieberman on its own -- or it might not have. But Obama's signal last week to extend Lieberman a Get-Out-of-Jail-Free Card was the immediate cause of that decision. Conversely, Obama could probably have engineered the opposite result if he'd wanted. (Nor is this to dispute the characterization of the Senate Democrats -- and particularly the Majority Leader -- as being somewhat weak-willed, but the practical implication of that is very different when you have a Democrat rather than a Republican in the White House.)
In our interview with him yesterday, Howard Dean dropped some very strong hints about what Obama is up to. We should expect him to be as methodical and meticulous about spending his political capital as he was about spending his advertising dollars and his ground game resources during the campaign. One can debate whether the Democratic caucus was more likely to achieve certain progressive policy outcomes with or without Lieberman in its ranks, but to Obama's mind, kicking him out would have been a giving both the Washington press corps and the Republicans a sort of shiny red apple, creating a huge distraction and requiring a significant expenditure of political capital.
So how you feel about Lieberman should ultimately hinge on how you feel about Obama, and how you feel about Obama should ultimately hinge on your opinion about whether he is liable to put that political capital to good use. If you believe Dean's implication that Obama is going to use that political capital to pass both significant climate change reform and significant health care reform within the first two years of his presidency, you probably ought to give him the benefit of the doubt. If, on the other hand, you see Obama as someone more concerned with the accumulation of power toward ambiguous, uncertain, or incorrect ends, this is liable to be the first of a long line of displeasing decisions, and you had better get used to pushing back against the White House.