Burningbird � Cheap Eats at the Semantic Web Caf�. Shelley on tags and folksonomies. Mmmm. I’m gonna be brief here: Shelley’s point seems to be: “tags won’t scale because they’re too easy and don’t contain enough semantic information” (flat namespace and all).
I don’t think that’s right. There is a LOT we can do to add semantics to tags: who created them, what namespace they come from (yes, most tags DO come from a namespace), algorythmical parsing of all kinds (related, …), mapping to controlled vocabs (use Wordnet to find synonyms or something). Look at the amount of innovation that has been done with search algorythms. The same can happen with tags.
That said, I do believe tags are strongest when tagging content that doesn’t contain text by and of itself (url’s, images, movies).