DynamicImport-Package is afair similar to Eclipse Buddy classloader which is a workaround for those that need to use hibernate and other libraries that uses dynamic classloading - it is not a solution. in other words, I don't think this is something Hibernate osgi metadata should officially include.

As discussed in Sweden (I thought notes from that was added here but I can't find it), what seem to be the right approach is that Hibernate declares its public/private API's and then make sure it works with some of the more official JPA service provider in osgi space out there.

One such example is Gemini at Eclipse http://wiki.eclipse.org/Gemini/JPA/Documentation/JPAServices
This is what EclipseLink works with and I think using that as a testbed for hibernate core/entitymanager would help define the right amount of osgi metadata Hibernate needs to declare and which things should be left to the service layers/users.

Other examples/docs around this approach can be found at:
http://wiki.eclipse.org/EclipseLink/Development/OSGi_Proof_of_Concept (note: the use of JPA-PersistenceUnits in manifest.mf)

Aries JPA at http://aries.apache.org/modules/jpaproject.html also seem to use similar notions.