I'm rather pleased with our own efforts at a group blog here, but Mark at Publius Endures, of whom I'm a fan, advises that he's begun a new group blog which seems promising. I also love the name: The League of Ordinary Gentlemen.
The focus seems rather political, and the writers diverse. In addition to Publius, a strong libertarian, they include Freddie DeBoer of the late, lamented, and dead blog L'Hote, Scott Payne of Politics of Scrabble, and Chris Dierkes of Culture11, along with a couple of guys I've never heard of.
Based on a cursory readthrough, the site seems well worth your time. Of course, we don't actually view any bloggers as competition, but we're so sure that we can beat these guys in the crucial Geek demographic that I'm adding them to our blogroll.
No law or politics blog can ever outgeek us.