system-tools-backend is in latest stable upstream version 2.0.x, gentoo is on 1.4.2. Maybe time for a bump? And when your at it you can change the homepage to http://system-tools-backends.freedesktop.org/ as it is its new home.
Ok, hold on this as it does not work with the current gnome-system-tools
Reopening to fix resolution.
This was applied to the tree. Thanks for reporting.