Social software: are we building networks or communities?

A recent posting by Stowe Boyd on community, trust, and social software from Anne Galloway reminded me of a distinction the poet Gary Snyder made at a workshop he led in Rochester, NY, promoting his book The Practice of the Wild. Gary said the networks are made up of people who attended conferences and shared similar ideas. Communities are composed of people who live together in a shared neighborhood or place, and who don't necessarily think alike or share similar values. This distinction has stuck with me. And it makes me wonder if social networks are "networks" or "communities"? They definitely feel to me more like "networks". But maybe we're experimenting with a hybrid, or something completely different?