gnome-control-center provides its own gui for configuring printers. It can be accessed by starting gnome-control-center and selecting the Printers icon or directly by running it from the command line as follows: "gnome-control-center printers". I don't understand why it has to depend on app-admin/system-config-printer-gnome. This is a completely independent program that is not needed for gnome-control-center's own printing gui to run. Moreover, system-config-printer-gnome[gnome-keyring] pulls in some gnome 2 dependencies which is undesirable. Am I missing something obvious here?
It's needed for "Add printer" function to work correctly (like finding the best driver): https://bugzilla.gnome.org/show_bug.cgi?id=698642