I coach communities of practice, their leaders, and their sponsors (sometimes about technology, sometimes about politics of learning). I help face-to-face, distributed, and (most commonly) communities that straddle several technologies and also meeet-face-to-face. My website / blog is at: http://www.learningalliances.net/.
I'm a community leader at CPsquare, the community of practice on communities of practice: http://www.CPsquare.org (which is a members-only community). I host a long-lived forum on communities of practice with open membership: http://www.yahoogroups.com/group/com-prac.
Of possible interest to people in the c2/wiki community, I've brought participants from the "Foundations of Communities of Practice" workshop (http://CPsquare.org/edu/foundations) to this Wiki to see what I think is a vigorous community that only has linguistic boundaries. (That is, there are few technical boundaries around it.) Some participants "get it" but many look at the community on this Wiki and they are completely baffled. So the barriers around this community are linguistic but not necessarily penetrable.
I also write about technologies from a community of practice perspective, currently finishing a book with Etienne Wenger and Nancy White titled "Digital habitats: stewarding technology for communitiess" (http://technologyforcommunities.com). One of the stories we tell in the book is about how Ward invented many tools to help him visualize what was happening on this Wiki in the midst of ongoing conversations with folks who were involved. In a way, Ward was one of the first people that were clear to me to be acting as "technology stewards," which ended up being a core concept in the book.