Lexi has been making a lot of progress on hyperjaxb3 lately.

HyperJAXB3 is a JAXB RI extension that causes XJC to generate not only XML binding annotations but also RDBMS persistence annotations. That is, it generates Hibernate mapping files, and the plan includes supporting the persistence API. He's also been investing in some infrastructure support, so that other folks can develop XJC plugins more easily.

For anyone who wants to play with the actual bits, he posted two sample projects that you can download today and use.

1. HyperJAXB3 hibernate sample that does Hibernate mapping generation.
2. HyperJAXB3 Persistence API sample that does JPA annotations.

See his "status report" posted yesterday for more details.