These are are some the changes:
- bug fixes
- there is a tightening up of the deployment descriptor parsing
- performance has been tweaked
- there is a basic SNMP module so JBoss can be monitored
- there is some sql checks for existing connections and new connections in the datasource configuration (<check-valid-connection-sql> and <new-connection-sql>)
There are probably other things as well. These are the only things I've noticed so far.