HOWARD KURTZ HAS A ROUNDUP on discussions of the difference between left and right blogs. I think a lot has to do with different purposes. As I wrote a while back:

What the September 11 attacks were to the warbloggers, though, the Democratic losses in the 2002 Congressional elections were to the left. Up to that point, though there were plenty of lefty blogs, the blogosphere tilted pretty solidly to the center-(libertarian) right.

But after that, the left worked hard to catch up. It didn’t hurt that the Democrats faced a contested primary season, which drew lots of Internet activists into the blogging fray. Between the Howard Dean campaign and the activism associated with anti-incumbency, the lefty side of the blogosphere expanded. And the character changed. When my own InstaPundit blog was newer, people sometimes wondered who would be the “InstaPundit of the left.” But what the left wanted more than punditry was activism, and sites like DailyKos are more like miniature political machines, concentrating on fundraising and get-out- the-vote efforts in a way that few right-wing sites do. Though talk-radio host Hugh Hewitt is starting to fill that niche, and no doubt others will, too, the right doesn’t have anything to match Kos this election cycle.

Since the media tilt heavily left, people on the right wanted alternative media. Since Republicans are better at grassroots organization, people on the left wanted grassroots organization. People on the left now have more political communities, while people on the right now have more freestanding pundits and alt-news sources.