Perhaps this will help until you get a more thorough answer . . . I believe you have to explicitly say that you want your Session object to be distributable. I don't know how you do this, and I'm not 100% sure I'm correct. But like I said -- maybe this can help until a guru gets to this question.
JBoss 3.0.4 has busted session-replication / clustering.
Use 3.0.6 and enable the JGStore in jbossweb.sar/META-INF/jboss-service.xml (search for JGStore).
And if you really can't figure it out, I will have updated docs on this at:
- click on "Setting up a JBoss Cluster"
It should be updated for 3.0.6 over next week.