"> For certain ontologies, java beans are a reasonable model. For
> others, though, with extremely flexible type systems, involving
> type relations outside those that map directly onto the java type
> system, its not so clear. Say it were possible for some instance to
> be a foaf:Person from one ontology and a deo:God from another
> ontology and a comic:Superhero from yet another, and there were no
> subclass relationships among these. Heck, perhaps deo:God and
> comic:Superhero both subclass from et:Nonhuman . While this isn't
> absurd by any means, it does make denoting the instance's type in a
> java bean complicated at best (I anticipate lots of interfaces ;-) ).
yes. My RDFHibernate library  works with interfaces that map onto
an RDF database using dynamic proxies."
It's listed under Java Distributed Data Acquisition and Control but does not seem available - except for the Subversion repository.
Henry Story just announced a new project which also has Hibernate overtones, Sommer "Sommer is a very simple library for mapping Plain Old Java Objects (POJOs) to RDF graphs and back. Sommer stands for Semantic Object (Metadata) Mapper. In German it also means "summer", the season opposite to winter, when animals no longer hibernate. In French a "somme" is both the sum of things as well as a little rest."