I'm not one who usually talks about blogs in revolutionary terms, but I have to admit that in terms of covering the campaign on-the-ground and actually providing a full picture of what it's like, they're succeeding where mainstream media has always failed. One can really get a pretty interesting narrative, or narratives, about what's going in Iowa from bloggers which I never see anywhere in the press. I don't think this is because a lot of the bloggers are "insiders" - working on the campaigns - I just think they're interested in telling the stories they see. Reporters could do this, but they don't.
The Dean site has set up Bloggerstorm (not all the bloggers are Dean supporters).
There's also the Blogging of the President.
