Cockpit and OpenLMI system management projects need systemd DBus API  to be authorized by polkit instead of plain DBus authorization.
See http://lists.freedesktop.org/archives/systemd-devel/2014-July/021262.html (and whole thread) for more detailed method list.
A patch has landed in systemd git master for polkit support, but it has not yet been released:
In addition it does not enable interactive agent based re-reauthorization. systemd upstream would like to create a DBus flag for that, and is being discussed here:
Fully implemented in git btw.
This is part of systemd 219 in F22+.