I have included his work on my 10 remarkable blogs you should read and 10 remarkable podcasts you should listen to posts. His book Six Pixels of Separation: Everyone Is Connected. Connect Your Business to Everyone. (Amazon affiliate link) is part of my required reading on my Internet Marketing course at Kozminski University.
Anyway, when Mitch Joel speaks … I listen (and I think you should too).
Back in February 2011 he gave a remarkable TEDx Talk in which he argues that the future of the web may not be social.