There haven't really been any major changes in packaging for EJB3. The main difference is just the new XML Descriptors -- other than that, it's pretty much the same as EJB-JAR from ejb 2.1, i.e..

your-ejb3-jar:
--- META-INF
-------- persistence.xml
--- your class hierarchy

and you can just import an ejb3 jar file into an ear like normal..