Hibernate just released a preview of their EJB 3.0 implementation: http://www.hibernate.org/247.html
This follows shortly after the release by Oracle of the EJB 3.0 Preview of the Oracle Application Server: Oracle Application Server EJB 3.0 Preview.
The goal of Enterprise JavaBeans (EJB) 3.0 is to simplify development of Java applications and standardize the persistence API for the Java platform. EJB 3.0 is expected to be part of the next major revision of the J2EE platform, J2EE 5.0. EJB 3.0 is being worked under Java Specification Request 220 (JSR-220) in the Java Community Process (JCP) and Oracle has been a major contributor to the development of the specification.
To date, the JCP has released several draft versions of EJB 3.0 specification against which Oracle has been implementing the Oracle Application Server EJB 3.0 Preview.
In Oracle Application Server EJB 3.0 Preview, Oracle has implemented most of the major features of EJB 3.0 Early Draft 2 specification. See the Features Overview
Hibernate, like all other object/relational mapping tools, requires metadata that governs the transformation of data from one representation to the other (and vice versa). In Hibernate 2.x, mapping metadata is most of the time declared in XML text files. Another option is XDoclet, utilizing Javadoc source code annotations and a preprocessor at compile time.
The same kind of annotation support is now available in the standard JDK, although more powerful and better supported by tools. IntelliJ IDEA, for example, supports auto-completion and syntax highlighting of JDK 5.0 annotations. The new revision of the EJB specification (JSR-220) uses JDK 5.0 annotations as the primary metadata mechanism. Hibernate3 implements the EntityManager of JSR-220 (the persistence API).
Please note that our current preview release of the Hibernate Annotations implements the Early Draft 2 Release of EJB 3.0/JSR-220 persistence annotations. However, we expect that this work is already very close to the final concepts in the new specification. Our goal is to provide a complete set of ORM annotations, including EJB3 standard annotations as well as Hibernate3 extensions for cases not covered by the specification. See the Compliance and Limitations section in the documentation for more information.