I deeply appreciate Joshua Porter's link to from his Taxonomies and Tags blog post. This is a discussion I have quite regularly as to the relation and it is in my presentations and workshops and much of my tagging (and social web) training, consulting, and advising focusses on getting smart on understanding the value and downfalls of folksonomy tagging (as well as traditional tagging - remember tagging has been around in commercial products since at least the 1980s). The following is my response in the comments to Josh' post...
Response to Taxonomy and Tags
Josh, thanks for the link. If the world of language were only this simple that this worked consistently. The folksonomy is a killer resource, but it lacks structure, which it crucial to disambiguating terms. There are algorithmic ways of getting close to this end, but they are insanely processor intensive (think days or weeks to churn out this structure). Working from a simple flat taxonomy or faceted system structure can be enabled for a folksonomy to adhere to.
This approach can help augment tags to objects, but it is not great at finding objects by tags as Apple would surface thousands of results and they would need to be narrowed greatly to find what one is seeking.
There was an insanely brilliant tool, RawSugar [(now gone thanks to venture capitalists pulling the plug on a one of a kind product that would be killer in the enterprise market)], that married taxonomy and folksonomy to help derive disambiguation (take appleseed as a tag, to you mean Johnny Appleseed, appleseed as it relates to gardening/farming, cooking, or the anime movie. The folksonomy can help decipher this through co-occurrence of terms, but a smart interface and system is needed to do this. Fortunately the type of system that is needed to do this is something we have, it is a taxonomy. Using a taxonomy will save processor time, and human time through creating an efficient structure.
Recently I have been approached by a small number of companies who implemented social bookmarking tools to develop a folksonomy and found the folksonomy was [initially] far more helpful than they had ever imagined and out paced their taxonomy-based tools by leaps and bounds (mostly because they did not have time or resources to implement an exhaustive taxonomy (I have yet to find an organization that has an exhaustive and emergent taxonomy)). The organizations either let their taxonomist go or did not replace them when they left as they seemed to think they did not need them with the folksonomy running. All was well and good for a while, but as the folksonomy grew the ability to find specific items decreased (it still worked fantastically for people refinding information they had personally tagged). These companies asked, "what tools they would need to start clearing this up?" The answer a person who understands information structure for ease of finding, which is often a taxonomist, and a tool that can aid in information structure, which is often a taxonomy tool.
The folksonomy does many things that are difficult and very costly to do in taxonomies. But taxonomies do things that folksonomies are rather poor at doing. Both need each other.
Complexity Increases as Folksonomies Grow
I am continually finding organizations are thinking the social bookmarking tools and folksonomy are going to be simple and a cure all, but it is much more complicated than that. The social bookmarking tools will really sing for a while, but then things need help and most of the tools out there are not to the point of providing that assistance yet. There are whole toolsets missing for monitoring and analyzing the collective folksonomy. There is also a need for a really good disambiguation tool and approach (particularly now that RawSugar is gone as a viable approach).