Well, lo and behold! While folks are discussing folksonomies on the METADATA list, the official conference wiki page has this
cetis-2006-conference
If you want to tag an item for a particular session, use one of these:
cetis-2006-conference-media
cetis-2006-conference-games
cetis-2006-conference-portfolios
cetis-2006-conference-accreditation
cetis-2006-conference-ple
cetis-2006-conference-architecture
cetis-2006-conference-institutions
cetis-2006-conference-unthinkable
Very nice example, if I may say so, of, not quite a controlled vocabulary, but the best kind of sort-of “guidance” vocabulary. This is the kind of thing we need if folksonomic tags are going to work better than the critics of Clay Shirky fear.
Why is that list not a controlled vocabulary?
I don’t think it counts as a controlled vocabulary simply because it isn’t controlled in any meaningful way. It is suggested, but not mandated. If one said this was a controlled vocabulary, then by extension one would have to say that a list I put up on my web site saying “use these tags when referring to me or my things” is a controlled vocabulary.