Thanks for the positive feedback!
Same as Bob - I have too a small success with bringing mod_cluster running. My configuration is as follows: 2 x JBoss AS 5.0.0.GA, 2 x Apache shipped in package with mod_cluster, all in an VMware environment (yes, without multicast) in non-clustered mode. I have two load balancers configured with Linux-HA (Heartbeat) and everything works really good!
I wrote an introduction to mod_cluster  on my blog .
Thanks for great work on mod_cluster!
 http://javavsme.wordpress.com/2008/12/07/mod_cluster-nowe-spojrzenie-na-load-balancery/ (in polish)
 http://javavsme.wordpress.com/ (also in polish)