After a month of hard work we have finally released the first open source version of Ontopia, which you can download from Google Code. This is the same product as the old commercial Ontopia Knowledge Suite, but with an open source license, and with the old license key restrictions removed.
The new version has been created by not just by the Bouvet employees who have always worked on the product, but also by open source volunteers. We are happy to say that the project is already functioning as a true open source project.
In addition to bug fixes and minor changes, the main new features in this version are:
- Support for TMAPI 2.0,
- The new tolog optimizer,
- The new TologSpy tolog query profiler,
- The net.ontopia.topicmaps.utils.QNameRegistry and QNameLookup classes have been added, providing convenient lookup of topics using qnames.
- Ontopia now uses the Simple Logging Facade for Java (SLF4J), which makes it easy to switch logging engines, if desired.
Ontopia's Blog 
What is Ontopia for? Knowledge taxonomies? Could you kindly send me an example of the kinds of results you can get? Thanks, Luis
That’s a good question, Luis. We started a wiki page to collect examples.
Sounds great guys. Good wishes for your first Open-Source release.