Description of problem: New method of accessing gluster(RHS) volumes through samba involves the use of vfs plugin for gfapi. Version-Release number of selected component (if applicable): 3.6.9 patch thread: https://lists.samba.org/archive/samba-technical/2013-May/092420.html
this is a new feature and new features don't come into stable release branches by policy. If you want to include vfs_glusterfs you need to patch your samba packages. As it just got into master end of May 2013 it will be part of the next 4.1 release.