Brightonart is currently involved in a series of new developments on the Drupal module Taxonomy NCO - AKA 'Matchy matchy', this module derives inferred semantic relationships from large folksonomies that tend otherwise to fragment and become unmanageable.
The module was originally developed in Drupal 5 as part of the School of Everything project. I am reposting this original blog post to preserve some technical background:
We've been working on an interesting new system over the past few years in the field of semantics.
It all started out with a big problem at the School of Everything. People were searching for music teachers and not finding people that had tagged their teaching profiles with piano. People looking for Martial Arts weren't finding teachers tagged with Tai Chi. The freetagging subjects vocabulary was getting out of control and the community was fragmenting as it expanded.