Jena 1.3.0 has been released. From the freshmeat page:
Jena is Java toolkit for developing semantic Web applications. It includes an RDF API, ARP, an RDF parser used for the W3C semantics Web sandbox, RDQL (an RDF query language and processor), and a DAML API.
The web page at HP Labs is very informative. Also of note is the next generation Jena2 project.