Tagging is a way that users can organize online information, using their own terminology. Pew Internet & American Life Project found that, in its December 2006 survey, 28% of internet users have tagged or categorized content online such as photos, news stories or blog posts.
So how could tagging be best used with user documentation?
Off the top of my head, intranet users could be enabled to tag sections of documentation, based on how they used/found/rated usefulness of the section. I’ll have to think about this some more and get back to you :-).