Has MemoryFileFactory been deleted in favor of a different class perhaps?
Yeah, the in-memory stuff was removed in VFS3.
See the "port" in our resurrected in-memory deployer:
* http://anonsvn.jboss.org/repos/jbossas/projects/jboss-deployers/trunk/deployers-vfs/src/main/java/org/jboss/deployers/vfs/plugins/classloader/InMemoryClassesDeployer.java