Today's NY Times editorial, in a nutshell:
While Hillary Clinton is unwilling to "risk political capital for principle," and "has hardly been a profile in courage" on the war, she is nevertheless not quite as bad as Lieberman. Also, she "works well" with Republicans. Tasini, on the other hand, might ruffle the feathers of "egotistic and generally conservative politicians" in Washington. And we can't have that. Therefore, the Times endorses the incumbent.
There, I just saved you the trouble of reading the whole thing.