Yeah, I also vote for import filter option in order to prevent some packages/classes to be accessible from within the app. Something like Filtering Classloader on WebLogic for example: http://download.oracle.com/docs/cd/E12840_01/wls/docs103/programming/classloading.html#wp1097187 would do the trick.
In particular I'm packaging some stuff in the app (like hibernate, jaxb etc) which exists in JBoss as well and I don't want to use those from JBoss in my app.
AFAIK this isn't currently possible to achieve on JBoss in the easy way. Or am I wrong?
Also the documentation for this classloding configuration is in very bad shape. There are pieces here and there, one must read sources sometimes etc. That really ****. A good, comprehensive documentation with simple and explained examples - all at one place - would be great.