David Weinberger goes back and forth on the use of tags:

Forth: But, language changes through implicit evocations of meaning. There is no word dictator who declares "Thou shalt now replace the word 'idea' with 'meme.'" Nope, we hear the word, get a sense from context or from a bumbling, hand-waving definition from someone at a party, and we appropriate it. After a while, a dictionary notices and attempts to freeze and formalize the definition. Yet, tags are explicit. They take something as rich in meaning as a family photo and reduce it to a single word. That's a diminishment.

Back: Big freaking deal. Categorization diminishes. Everyone knows that. It's why we categorize: It reduces complexity to something manageable at least for the moment. But often categorization diminishes so that things in their richness can be found: Menus in restaurants categorize food so you can taste it in all its glory. And if people feel that the popular tags are not categorizing objects the way they want, they can build local folksonomies, using the tags accepted by their social group.

Forth: Not in the commercial world. Steve Papa at Endeca at the PCForum open discussion a few days ago pointed to eBay as an example: There are economic reasons to describe your items for sale using the most popular language. E.g., call it a "notebook," not a "laptop." Likewise, where there are economic or other reasons for people to use the popular tags, some folksonomies will dominate. This will undoubtedly drive some ambiguity out of our everyday language. For example, someone pointed out to me recently that CNN started out calling the tsunami a "tidal wave," but switched when everyone else was calling it a "tsunami." That sort of thing will happen faster and more regularly as folksonomies grow in more and more fields