Found the answer from tomcat's faq:
"7. How do I share sessions across webapps?
You cannot share sessions directly across webapps, as that would be a violation of the Servlet Specification. There are workarounds, including using a singleton class loaded from the common classloader repository to hold shared information, or putting some of this shared information in a database or another data store. Some of these approaches have been discussed on the tomcat-user mailing list, whose archives you should search for more information.
Sharing sessions across contains for clustering or replication is a different matter altogether."
If my wars are all in a single ear, is there perhaps a solution using JBoss' single classloader for the one ear?
Any ideas/experience with this?
There must be some experiences :-)