The new ring to grab on the marketing merry-go round is social bookmarking.
Tags and Digg started out as elegantly simple ways of sharing information online. But just like folksinging in the 60's, folksonomy has gone from the folk to big business. And the pool of information has gotten muddy.
For an eye-opening look at what's happening to Web 2.0 see Digg Dirt: An Ongoing Examination of Social Bookmarking on IAOCblog.