2.4.4 holds all messages in memory while they are sitting around to be picked up by a consumer. 2.4.4 also had a few memory leak bugs that occured when using pub/sub. 2.4.5 has fixed those leaks. 3.0.x now passivates messages that have been sitting around for too long on the server.
There is no 2.4.5 on the download site (http://www.jboss.org/binary.jsp) and the online documentation (http://jboss.org/online-manual/HTML) only addresses 2.4.1 (jms) or below, right? Where can I download 2.4.5 and/or where can I read how to configure 3.x (like the jboss.jcml and jndi.properties in 2.4.4)?