Amy Bruckman responds to Clay Shirky

Excellent point, Clay. I find Wikiprojects on Wikipedia fascinating because they are an attempt to create collaborative sub-groups of functional size within one of those large-scale collaborative settings. And there's some great empirical evidence (for example by Niki Kittur at CMU) that they work. See for example:

"Herding the Cats: The Influence of Groups in Coordinating Peer Production?" by Aniket Kittur, Bryan Pendleton, and Robert E. Kraut. Proceedings of Wikisym 2009.
http://www.wikisym.org/ws2009/procfiles/p107-kittur.pdf