We are using 4.2, I came accross the following is this is still valid for 4.2:
Note: For BMT beans, do not obtain the UserTransaction interface using a JNDI lookup. Doing this violates the EJB specification, and the returned UserTransaction object does not have the hooks the EJB container needs to make important checks.
http://docs.jboss.org/admin-devel/Chap4.html
