Yes, I definitely agree about *also* including user-defined tags of some type (which would have to have some kind of control coming from the library…imagine the kind of tags that some patrons might assign to materials on abortion, for example, or the Holocaust; I doubt that most libraries are going to be comfortable implying that they endorse certain viewpoints by letting the tags remain in their catalogs). And if there are automated tools to help with all of this–bring them on!!

I couldn’t agree more except that one must keep in mind the potential of automated systems to implement the use of controlled vocabularies and cataloguing mark up of some kind. The future will probably be more collaborative and ‘open’, where XML records will have controlled access fields and at the same time have user-defined tag style fields. With the latter you would want some kind of daemon running on your system that checks and updates the non-controlled keywords in real time or over night, checking for duplicates, mis-spellings and maybe referring to some kind of controlled vocabulary.