I think the lesson from "web 2.0" apps is that if you make something easy to use and useful, people will use it. So the rise of folksonomies is about usability,

I think the lesson from "web 2.0" apps is that if you make something easy to use and useful, people will use it. So the rise of folksonomies is about usability, not doing away with structure. In my experience, if you can make entering more structured metadata just as easy, people will enter it, and you get a big return in the ability to use the information you've collected.