Dan Farber has an interesting piece today about how user-contributed metadata will revolutionize online advertising. He mentions Facebook, Metaweb and Twine as examples. I agree, of course, with Dan's thoughts on this, since these are some of the underlying motivations of Twine. The rich user-generated metadata in Twine is not just about users however, it's about everything -- products, companies, events, places, web pages, etc. The "semantic graph" we are building is far richer than a graph that is just about people. I'll be blogging more about this in the future.