LibraryThing is now showing relationships between LC subject headings and user-assigned tags and the results are really interesting. Lots of forward-thinking librarians and web-2.0-ologists have been claiming for a while that subject headings and tags can coexist without eating each other’s babies, but we haven’t had any place to see it in action until now. (PennTags, for example, incorporates tags in the catalog, but doesn’t show relationships between tags and subject headings.)

It’s really pretty cool how much information can be derived simply by observing the co-occurrence of tags and subject headings, without any directed human input matching them up.

I think RJO’s comment on this post (the second one) is pretty insightful. I’ve been noodling around with LibraryThing and listening in on the LibraryThing Google Group, and one of the things that occurred to me as well was that it might be useful to have private tags, for things like shelf location and read/unread status, in addition to public tags, which really make sense in the social-networking atmosphere connecting up tags and subject headings and everything.

The library world is going to be continuing to watch LibraryThing for interesting experiments in bibliography. It’s a perfect test-bed for these kinds of things, because its user-base is a dedicated one that cares about adding tags, etc., because they are their books. I don’t know how easily any of this translates to the catalog for a particular library, because the average dedication level for users is lower, but there are potentially lots more users as well. As we see more experiments like this, time will tell.