This will be moot on M3. We have entirely replaced JBoss Messaging by HornetQ on JBossAS/trunk (what will become M3 in a few weeks).
You will have hornetq already installed If you build JBoss/as from trunk.
You can either build AS6 from svn and test if this issue is gone... or download it the latest successful nightly build:
http://hudson.jboss.org/hudson/job/JBoss-AS-6.0.x/lastSuccessfulBuild/artifact/JBossAS_6_0/build/target/jboss-6.0.x.zip
From the POV of HornetQ / Messaging everthing is pretty much ready now on AS6.