I just read a good summary of taxonomies (formal, forced-choice method to categorize information) vs. folksonomies (organic tagging method to organize information) in KM World; this author felt they were not equal and definitely not interchangeable. I am really glad someone has formally stated that.
Tagging does not necessarily create a repeatable, easy-to-find organizational structure. Tagging is great if your objective is to raise the most popular items to the top, which might work for certain organic sharing like in forums, blogs or social network sites. I have played with both and have found that there still is a need to have a standard classification method to help people find information especially for formally published items, like documents.
Now, that standard taxonomy must be maintained, reviewed and updated to reflect new products, programs and vernacular within an organization. Too often, a taxonomy is set and forgotten about until five years later no one can find anything because a product is no longer called “value statement” but, rather, “value proposition”.
One way to compensate for those changes is to create a synonym in your search tool so that they equal each other. This is why I am such a big fan of search. However, in the workplace, I have observed that many people prefer to browse over search. Yet, in their personal lives, they would never browse the Internet, they use Google. This is a really astounding phenomenon to me and one that deserves a good deal of change management attention.
Until internal search becomes perfected, a sound taxonomy is needed but so is tagging. I still balance both. I ask users to select a formal category but also allow them to free-form tag the document as well. Those tags provide valuable insight into how people might search for information and how we may need to evolve the taxonomy!