Information architecture can have different layers, some of which evolve quickly and some of which evolve slowly.
For example, we could have a slowly evolving layer of managed, centrally approved ControlledVocabularies. But on top of that, we could have a quickly-changing layer of [[folksonomy?]].
This approach allows us to gain many of the benefits of both layers. For example, by using the ControlledVocabulary when possible, it would be easier to know how to search for an item (because there is more assurance that items that belong together will be grouped under the same index terms). By using the [[folksonomy?]] for new concepts that aren't yet in the ControlledVocabulary, we mitigate the bottleneck that new ControlledVocabulary terms must be approved by the central authority, and therefore won't keep up with life.
OK, this page name is pretty long…. any other ideas?