Web 2.0 has been all the rage on the InterWeb (for you not-in-the-know, web 2.0 [wiki] is a buzzword for web-based communities or user-created contents)
Kathy Sierra of Creating Passionate Users blog had a post a while ago about distinguishing "wisdom of crowds" from "dumbness of crowds".
"Collective intelligence" is a pile of people writing Amazon book reviews.
"Dumbness of Crowds" is a pile of people collaborating on a wiki to collectively author a book.(Not that there aren't exceptions, but that's just what they are--rare exceptions for things like reference books. I'm extremely skeptical that a group will produce even a remotely decent novel, for example. Most fiction suffers even with just two authors.)