In this article I will show you how to install Gnome 3.8 on OpenSUSE 12.3.
The easiest method for installing Gnome 3.8 is to update a previous version of it.
$ sudo zypper install gnome
Or, if you already have Gnome installed, just update it with the following commands.
$ zypper ar -f obs://GNOME:STABLE:3.8/openSUSE_12.3 GS38
$ zypper dup --from GS38
This is it. Enjoy.