In Wired, Bruce Sterling weighs in on folksonomies:

Folksonomy emerges from a combination of two inventions: (1) machines that can automate at least some of what it takes to classify information and (b) social software that makes users willing to do at least some of the work for nothing. You'll notice that 1 and b don't really go together. Folksonomy is like that. A pinch of free work and a peck of mechanical sorting will get you from 1 to b. Examples, which include the social bookmarking Web sites del.icio.us, furl.net, and jots.com, are proliferating.

The Flickr photo-sharing service harnesses the power of folksonomy to organize a mighty torrent of images flowing from the world's digital cameras, phones, and PDAs. The principle is simple: It's a drag to name or describe the zillions of private photographs you shoot each year, but that labor is a lot less onerous to people who like to surf snaps online.

Thus, Flickr breaks up the world into folksy categories that genuinely interest the online audience. In Flickrland, the world is composed of Architecture, Beaches, Cameraphones, Dogs, Europe, Friends, Graffiti, Honeymoons, and on and on. Nobody invented this scheme, and best of all, it's an ongoing, democratic process. It's a product of group interaction, like footpaths trampled across a virgin wilderness by a herd of bison.

A folksonomy is nearly useless for searching out specific, accurate information, but that's beside the point. It offers dirt-cheap, machine-assisted herd behavior; common wisdom squared; a stampede toward the water holes of semantics. There's room for scholarly smarts in this approach - for instance, you might invent a really cool term like folksonomy - but mostly, it's a new way to crowd-surf. It's as though you threw a kayak into a mosh pit and glided not just through Web pages but through labels, concepts, and ideas, too.

...via Get Real