libvirt ACLs

I was looking at /etc/libvirt/libvirtd.conf on a RHEL 7.0 machine (libvirt 1.1.1) and a RHEL 7.1 beta machine (libvirt 1.2.8), and I saw that there is an option to enable libvirt ACLs.

# Change the API access control scheme
#
# By default an authenticated user is allowed access
# to all APIs. Access drivers can place restrictions
# on this. By default the 'nop' driver is enabled,
# meaning no access control checks are done once a
# client has authenticated with libvirtd
#
#access_drivers = [ "polkit" ]

However, I cannot find any documentation on libvirt ACLs in the RHEL documentation. I can only find libvirt project documentation and some info from the Fedora project.
http://libvirt.org/aclpolkit.html
http://libvirt.org/acl.html
http://fedoraproject.org/wiki/Changes/Virt_ACLs
http://fedoraproject.org/wiki/QA:Testcase_Virt_ACLs

As a sysadmin who maintains only 1 RHEL KVM host at work (and therefore would not use full-blown RHEV), this sounds like a great feature. Has anyone used libvirt ACLs successfully?