This overlay allows you to build latest git version of mesa and wine with the gallium nine patches. Wine has to translate DirectX => OpenGL => Gallium, which add complications and brings inefficiency. Thanks to the gallium nine state tracker we simply skip the OpenGL translation. More info here: http://ixit.cz/faster-wine-games-with-open-source-drivers-d3d9-aka-gallium-nine/
This patchset is maintained by David Heidelberger (here you can find his work).
You can find my media-libs/mesa-9999 and app-emulation/wine ebuilds with gallium nine patches in the new wine-nine overlay: http://www.linuxsystems.it/overlay/