It was announced today by Robert Ancell at Canonical that right now they're running on a heavily-patched version of GNOME 3.6 and that they're not looking forward to upgrading the gnome-control-center version since it would involve a lot of work. Right now Canonical carries 61 patches atop the gnome-control-center and they are uninterested in upgrading the patches against the latest GNOME software code.
As a result, Canonical has decided to fork GNOME Control Center into the Unity Control Center. With this approach, GNOME Ubuntu users will at least be able to install the upstream gnome-control-center package without running into any packaging collision issues. The stated intention of Unity Control Center is to provide stability and security fixes until the future Ubuntu System Settings project is complete. Ubuntu System Settings is a completely new configuration center for Ubuntu on desktop and mobile devices still being developed at Canonical.
News of forking the old GNOME Control Center was made today on the ubuntu-desktop list.