Ontopia has contained an automatic classification module under the covers for a while, but it was never documented, and there was no real interface to it, and so nobody looked at it. The module has now been properly documented for version 5.1.0, and a command-line interface has been provided.
The Ontopia web site now has a page about the classification, describing what is in the product. There is also an old presentation with some background information.
Ontopia's Blog 