Peter Merholz takes on Clay Shirky in peterme.com: Clay Shirky's Viewpoints are Overrated: Clay's whole argument predicates a black-and-white distinction between evil hierarchy on one side and good tags on the other... And while Clay is right to question hierarchy, and, particularly, Yahoo's less-than-optimal use of it, he neglects to distinguish truly useful forms of professionally-created classification and categorization, which undermines his argument. (He continues to set tags against folders-and-hierarchies, as if there are no other ways of classifying information. Sigh.)