Shane Johnson has written a multi-part article that covers migrating Java EE 5 applications to Java EE 6 technology. Its sample code is a working project. In the series Shane shows how you can make the most of new technologies such as Arquillian, CDI and JAX-RS.
Sande Gilda has written a guide to migrating from JBoss AS 5 or JBoss AS 6 to JBoss AS 7. This guide focuses on running your application unchanged.