They were getting beat out by Facebook and LinkedIn. What has happened with Orkut, Friendster, Tribe.net, and other SNS (social networking sites)? Will they adapt, consolidate, or disappear? Seems like a good case study of an emerging field of competitors. Do new rules apply, or the same old industrial organization and strategic evolution? Or, like the persistent synthetic worlds Castronova described (like Ultima Online), will they persist due to the stickiness of social ties?