The past few weeks have seen my inbox flooded with folksonomy questions. I am going to make things easier on my inbox by posting some common discussions here. Many of the items I am posting I have posted else where, but this will also be a great help for me.
There have been many people who have correctly discerned a difference between the two prime folksonomy examples, Flickr and del.icio.us. As I first stated in a comment to Clay Shirky's first article on Folksonomy, there are two derivations of folksonomy. There is a narrow folksonomy and a broad folksonomy. On August 26th I stated...
Clay, you bring in some very good points, particularly with the semantic differences of the terms film, movie, and cinema, which defy normalization. A broad folksonomy, like del.icio.us, allows for many layers of tagging. These many layers develop patterns of consistency (whether they are right or wrong in a professional's view is another matter, but that is what "the people" are calling things). These patterns eventually develop quasi power law for around the folk understanding of the terms as they relate to items.
Combining the power tags of "skateboarding, tricks, movie " (as you point out) will get to the desired information. The hard work of building a hierarchy is not truly essential, but a good tool that provides ease of use to tie the semantic tags is increasingly essential. This is a nascent example of a semantic web. What is really nice is the ability to use not only the power tags, but also the meta-noise (the tags that are not dominant, but add semantic understanding within a community). In the skateboarding example a meta-noise tag could be gnarly that has resonance in the skate community and adds another layer of refinement for them.
The narrow-folksonomy, where one or few users supply the tags for information, such as Flickr, does not supply power tags as easily. One or few people tagging one relatively narrowly distributed item makes normalizing more difficult to employ an tool that aggregates terms. This situation seems to require a tool up front that prompts the individuals creating the tags to add other, possibly, related tags to enhance the findability of the item. This could be a tool that pops up as the user is entering their tags that asks, "I see you entered mac do you want to add fruit, computer, artist, raincoat, macintosh, apple, friend, designer, hamburger, cosmetics, retail, daddy tag(s)?"
This same distinction is brought up on IAWiki' Folksonomy entry.
Since this time Flickr has added the ability for friends and family (and possibly contacts) to add tags, which gives Flickr a broader folksonomy. But, the focus point is still one object that is being tagged, where as del.icio.us has many people tagging one object. The broad-folksonomy is where much of the social benefit can be derived as synonyms and cross-discipline and cross-cultural vocabularies can be discovered. Flickr has an advantage in providing the individual the means to tag objects, which makes it easier for the object to get found.
This brings to the forefront the questions about Google's Gmail, which allows one person the ability to freely tag their e-mail entries. Is Gmail using a folksonomy? Since Gmail was included in the grouping of on-line tools that were in the discussion of what to call these things (along with Flickr and del.icio.us) when folksonomy was coined I say yes. But, my belief that Gmail uses a folksonomy (regular people's categorization through tagging) relates to it using the same means of one person adding tags so that object can be found by them. This is identical to how people tag in Flickr (as proven by the self-referential "me" that is ever prevalent) and del.icio.us. People tag in their own vocabulary for their own retrieval, but they also will tag for social context as well, such as Flickr's "MacWorld" tags. In this case Wikipedia is a little wrong and needs improving.
I suppose Gmail would be a personal folksonomy to the Flickr narrow folksonomy and the del.icio.us broad folksonomy. There are distinct futures for all three folkonomies to grow. Gmail is just the beginning of personal tagging of digital objects (and physical objects tagged with digital information). Lou Rosenfeld hit the nail on the head when he stated, "I'm not certain that the product of folksonomy development will have much long term value on their own, I'll bet dollars to donuts that the process of introducing a broader public to the act of developing and applying metadata will be incredibly invaluable.". These tools, including Gmail, are training for understanding metadata. People will learn new skills if they have a perceived greater value (this is why millions of people learned Palm's Graffiti as they found a benefit in learning the script).
Everybody has immense trouble finding information in their hierarchal folders on their hard drive. Documents and digital objects have more than one meaning than the one folder/directory, in which they reside. Sure there are short cuts, but tracking down and maintaining shortcuts is insanely awkward. Tags will be the step to the next generation of personal information managment.