The stabling of most of Gnome 2.24 has broken the gnome-light-2.22 ebuild, since it depends on >=2.22 ebuilds. Some packages (e.g. gnome-control-center) are still only stable for 2.22 and do not build against 2.24 packages. So it seems we need a few keywords (gnome-light, gnome-control-center).
Thanks for the heads up, marked ~ppc and ~ppc64.