Do Tags Work?
tekka.net
tekka.net
Flickr tags are by people categorizing their own photos (that is, publisher-generated categorization.) Not people categorizing things they've found or aren't theirs. This leads to radically different behavior. Given this is a librarian, the second case is much more relevant and interesting.
One analysis without understanding the space or how the subject differs from the desired outcome (that is, categorization) seems very embarassingly shallow.
(Yes, this annoyed me the first time I read it, a while ago.)