I disagree with Adena's take on Planet Geospatial as a group blog. Boing Boing is a group blog. The GeoRSS Blog is a group blog. The Stoa Consortium is a group blog. Planet Geospatial is a feed aggregator. I've worked with James Fee to get markup that is easy to monkey with, but that's as far as I consider it a joint venture. Not that I'd be opposed to participating in a group blog.
Speaking of the blogosphere: I'm looking to blog swap for a week or so with a food or wine blogger that has a equal itch to try writing about the software and data side of viticulture, terroir, geography, and maps. Interested? Send me an email.