Hmm, using 4.0.4RC1 I get always a NPE when I try to create an EM factory:

javax.persistence.PersistenceException: java.lang.NullPointerException
at org.hibernate.ejb.Ejb3Configuration.createEntityManagerFactory(Ejb3Configuration.java:173)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:103)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:37)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:27)
at foo.CatalogImportSLSB$ImportThread.(CatalogImportSLSB.java:84)
...

code snippet:

@Stateless
public class CatalogImportSB implements .... {

 class ImportThread extends Thread { ...
 private EntityManagerFactory emf;
 private EntityManager em;
 public ImportThread(CatalogImportProfile profile, byte[] data,
 String clientId)
 {
 emf = Persistence.createEntityManagerFactory("puname");
 em = emf.createEntityManager();
 ...
 }
 }

 @PersistenceContext(unitName="puname")
 EntityManager em;

 @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
 public void importCatalog(CatalogImportProfile profile, ...) {
 ...
 ImportThread it = new ImportThread(profile, data, clientId);
 it.start();
 ...
 }