I have also experienced this problem as we were anxious to anaylize the modifications we need to make to move to JBoss 5.
It seems that they decided to strictly implement the application.xml now as well, so that in a single ear it will fail the ear deployment if there are more than one wars with the same context even though they belong to different virtual hosts, since the virtual-host element was usable in the application.xml in 4.2 but not in 5.
Any idea on whether this situation is being considered and if a solution for it is being created?
Any help or pointers would be greatly appreciated
This has been fixed for the upcoming 5.0.1.GA release.