Unity

Unity is an alternative shell for the GNOME desktop environment, developed by Canonical in its Ayatana project. It consists of several components including the Launcher, Dash, lenses, Panel, indicators, Notify OSD and Overlay Scrollbar. Unity available in two implementations: 'Unity' is the 3D accelerated version, which uses Compiz window manager and Nux toolkit; and 'Unity 2D' is a lighter alternative, which uses Metacity window manager and Qt toolkit.

GCC
Should use 4.6.3.

Python
Should use 2.7 and not 3.2.

Installation
You can install Unity with unity-base/unity-meta ebuild, can be found in the unity-gentoo overlay in layman:

If you experience blocks with regard to x11-libs/qt packages, then do:

Usage
Should run Unity with GDM.

External resources

 * unity-gentoo overlay
 * Overlay unity-gentoo thread on Gentoo Forum
 * Unity article in Arch Linux Wiki