If you use systemd, you will need to add the systemd overlay.

Use this overlay at your own risks, I assume you know what you're doing and how to repair a broken system.
Some are ebuilds from tree with modified deps to allow using for example gnome-shell...
Some are new ebuilds.

You are supposed to be using ~amd64 or ~x86 if you use this overlay

Please report any failure or missing dep.
You can also request to add any ebuild.

WARNING : One of the main goals of this overlay being to use a usable gnome-shell trunk, some really unstable gnome stuff should be coming during the next weeks/monthes, you should mask what you don't want to see on your system ;)

Marc-Antoine@Perennou.com