These ebuilds come from http://sabayon.org.
If you have some problems, go to the official site first.
gnome-shell : Provides core UI functions for the GNOME 3 desktop ( https://wiki.gnome.org/Projects/GnomeShell )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a sabayon
For Paludis use this rsync : rsync://gentoo.zugaina.org/sabayon-portage
If you have a problem : ycarus(-at-)zugaina.org