I think you foreshadowed this last week when you posted about bloggers having to toe the conservative-leaning-libertarian line, but I still don't see what you see. TNR is smart and incisive every day. Josh Marshall is not only a liberal blogger but also a good reporter. Protoblogger Kaus is unsparing, even if he has become a wholly owned subsidiary (and wouldn't we all sell out like that!). Easterbrook is a great snarky-but-fair liberal.
I don't have much use for this Limbaughtomy crap; honestly, it's just a mirror image of Limbaugh himself -- lots of cutesy name-calling and little actual thinking. It's boilerplate, like reading Atrios. I don't doubt that there are true-believing Democrats out there; that's dandy. But if I want to be fed the party line, I'll go to the DNC website. In fact, few things make a blogger more interesting than a little hand biting. Kaus, on the left, and Sullivan, on the right, are good examples: Happy to trumpet their agreement with their party, but merciless in excoriating the hacks and hangers-on. (In fact, Kaus seems to have an affirmative-action program for beating up on hacks: those in his own party go to the top of the list.)
I dunno. Maybe I'm just getting grumpy. It's like the Hannity thing. One of the radio shows I like gets bumped for Hannity occasionally. Now, the usual host is certainly conservative. But he's an interesting conservative, not some bland white guy soft-soaping family values or similar pabulum. When Hannity is on, I'm just not learning anything, not hearing anything new. The same thing happens when I read Ann Coulter. She gets off a good zinger now and again, but there really isn't any substance there.
I'm certainly not opposed to the rough and tumble of partisan discourse. I like hearing a liar called a liar, a bum being called a bum. But the "Bush lied, people died" formulation (like the Clinton-killed-Vince-Foster stuff) is so old and intellectually unhelpful (and widespread) as to be media white noise.