Collaborative tagging

What is the role, place and benefits of emergent bottom-up classification?

Tagging is taking hold, if we like it or not. Del.icio.us, Flick'r, Technorati and other applications are leading the way, showing how user-applied tags can be useful, social and self-maintaining. This interview covers open source tagging tools.

A recent review (which I discovered via the del.icio.us tag "knowledge") lists the benefits and the downsides of the genre.

I have found tagging to be a very useful way to seed & build a controlled vocabulary and keyword classification system for small virtual teams. It helps when users can find the labels that carry maximum meaning for them and are not forced into an imposed system of permitted keywords.

Folksonomies have their upsides and their downsides as stated in this post. It pays to be aware of the benefits and the pitfalls, watch for scalling issues, steer towards shared meaning and limit (redundant) synonyms.

Tagsonomy blog is a great place to keep abreast of current opinion in this area with writings by the leading thinkers.

So what are your thoughts on tagging?