PolicyKit is a framework for defining policy for system-wide components and for desktop pieces to configure it. It is currently used by several components of the GNOME desktop, among which GConf, NetworkManager, the gnome-system-tools. GNOME does not depend on PolicyKit1 itself, but on polkit-gtk-1. Please note that version 1 is not compatible with its predecessors (versions below 0.92).
Documentation for the version 1