I notice that if you have two (or more) web apps deployed which all have the same .jar in WEB-INF/lib, then you make a change to a class in the .jar, redeploy the web app... that change is not reflected until you redeploy ALL web apps which use the .jar ! It's almost as if the container uses a single instance, and tries to make all web apps share it.
Did you find a way to fix this?. I have the same problem with 3.2.3 with singletons across WebApplications.
I read somewhere that we have to enable Servlet 2.3 model classloader to fix this. Can't find where the settings are(seems we have to do it in tomcat-service.xml).
I think it might pertain to the universal classloader repository. There is a thing you can add in the jboss-app.xml if you deploy as an EAR. I'm encountering weirdnesses that seem to be stemming from the same source of problems as you folks are.