'm using:
hibernate core 3.2.4 sp1
hibernate entitymanager 3.3.1GA
hibernate annotations 3.3.0 GA

but I always got the following error:
2007-07-14 18:21:54,421 ERROR [org.jboss.ejb.plugins.LogInterceptor] EJBException in method: public abstract hermes.simulate.ejb.SimpleEntityManager hermes.simulate.ejb.SimpleEntityManagerHome.create() throws javax.ejb.CreateException,java.rmi.RemoteException, causedBy:
java.lang.reflect.UndeclaredThrowableException
at org.jboss.ejb.plugins.AbstractInstancePool.get(AbstractInstancePool.java:204)
at org.jboss.ejb.plugins.StatelessSessionInstanceInterceptor.invokeHome(StatelessSessionInstanceInterceptor.java:95)
at org.jboss.ejb.plugins.CallValidationInterceptor.invokeHome(CallValidationInterceptor.java:56)
at org.jboss.ejb.plugins.AbstractTxInterceptor.invokeNext(AbstractTxInterceptor.java:125)
at org.jboss.ejb.plugins.TxInterceptorCMT.runWithTransactions(TxInterceptorCMT.java:350)
at org.jboss.ejb.plugins.TxInterceptorCMT.invokeHome(TxInterceptorCMT.java:161)
at org.jboss.ejb.plugins.SecurityInterceptor.invokeHome(SecurityInterceptor.java:145)
at org.jboss.ejb.plugins.LogInterceptor.invokeHome(LogInterceptor.java:132)
at org.jboss.ejb.plugins.ProxyFactoryFinderInterceptor.invokeHome(ProxyFactoryFinderInterceptor.java:107)
at org.jboss.ejb.SessionContainer.internalInvokeHome(SessionContainer.java:637)
at org.jboss.ejb.Container.invoke(Container.java:975)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:86)
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
at org.jboss.invocation.jrmp.server.JRMPInvoker$MBeanServerAction.invoke(JRMPInvoker.java:819)
at org.jboss.invocation.jrmp.server.JRMPInvoker.invoke(JRMPInvoker.java:420)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:294)
at sun.rmi.transport.Transport$1.run(Transport.java:153)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:460)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:701)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.IllegalAccessError: tried to access method org.hibernate.cfg.Mappings.<init>(Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/List;Ljava/util/List;Lorg/hibernate/cfg/NamingStrategy;Ljava/util/Map;Ljava/util/Map;Ljava/util/Map;Ljava/util/List;Ljava/util/Map;Ljava/util/Map;)V from class org.hibernate.cfg.ExtendedMappings
at org.hibernate.cfg.ExtendedMappings.<init>(ExtendedMappings.java:65)
at org.hibernate.cfg.AnnotationConfiguration.createExtendedMappings(AnnotationConfiguration.java:166)
at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:254)
at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1039)
at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1233)
at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:154)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:869)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:183)
at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:240)
at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:120)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:51)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:33)
at hermes.simulate.ejb.SimpleEntityManagerEJB.<init>(SimpleEntityManagerEJB.java:28)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
at java.lang.Class.newInstance0(Class.java:350)
at java.lang.Class.newInstance(Class.java:303)
at org.jboss.ejb.Container.createBeanClassInstance(Container.java:625)
at org.jboss.ejb.plugins.AbstractInstancePool.get(AbstractInstancePool.java:183)
... 32 more