I am also interested in this.
As far as I know, Hibernate is not yet OSGiyfied so there will be problems when it comes to ClassLoading. Thats why I used EclipseLink within a Eclipse RCP for JPA. However, since AS 7 provides a OSGi-subsystem for web-bundles I expected some kind of integration. Is there a way to use Hibernate or would I have to leave the osgi-subsystem (calling an EJB for instance) which wrapps my data-access-logic?