From the New York Observer's Politicker blog, by way of Atrios, we learn that John Murtha has said that he would campaign for Ned Lamont if asked. I haven't seen a whole lot of commentary on this, but I think this is huge, and Lamont must take him up on it.
I'm not saying this because Murtha is a darling of the left right now for his antiwar stance; in fact, my reasoning is almost exactly the opposite: Lamont needs Murtha to campaign for him precisely because Murtha is so far to the right. One of Lieberman's favorite myths about himself that he tries to peddle to voters is that he's some kind of principled bipartisan moderate, and that he's being purged by an ideologically intolerant Democratic party (and/or rabid left-wing bloggers). John Murtha is probably to the right of Lieberman on most issues except the war, and yet his behavior is the exact opposite: He doesn't suck up to the president, he doesn't parrot Republican talking points, and he speaks out forcefully against the war and generally kicks Republicans' butts.
I believe that if a genuine principled moderate like Murtha campaigns for Lamont, it will drive the message home that Lieberman is not a principled moderate, but a Republican suckup; and that capitulation is not bipartisanship. Murtha's support will be much more difficult to dismiss than that of anyone else who has campaigned for Ned, because he is so much harder to paint as a member of the Radical Unhinged Angry Left Trying To Purge All Moderates From The Congress. Not that Lieberman and the Republicans won't try, of course.