Yochai Benkler has written at length about Open Source software development, and its extension into what he calls generalized "commons-based peer-production," to distinguish collaborative projects like Wikipedia and the Linux kernel from traditional modes of strictly commerce-driven economic practice. The history of commons-based peer-production on the Internet has yielded some insight into the types of organizing structures these projects use to grow and evolve in the absence of the traditional carrot-and-stick arrangements of business and academia. Tim O'Reilly loosely terms these structures "the architecture of participation", but is the definite article he uses somewhat misleading?

In his classic work "A Pattern Language", Christopher Alexander lays out the thesis that truly successful and humane building architecture can be broken down into design patterns with distinct features and attributes that can be combined to generate new architectural designs. In the software world, Alexander's work is best known through its extension to software engineering put forward in the 80's by Kent Beck, Ward Cunningham, and others. Our key question is: Is there some way in which the "architecture of participation" in collaborative projects also evince a "pattern language"? In pursuing this question, we may discover not a single architecture of participation, but many different ones, composed of related practices.

We'll examine multiple architectures of participation in online collaborative projects, from Craigslist to Apache to Wikipedia and OpenStreetMap, and look for identifiable patterns that can be abstracted into a grammar. What, for example, are the social rules and technical affordances used by these projects to work collaboratively and to achieve and enact the results of group consensus? We'll see if we can't capture a few of the more obvious patterns, and look at how a successful participatory pattern in one instance might not be quite so successful in another. Hopefully, we'll have time to come full circle, and talk about what having a catalog of such patterns might imply for accelerating Open Source software, Free Culture, and this "Web 2.0" thing.