I've just added xorg-server 1.5 and mesa 7.1 to the tree as ~arch. They
will be part of the X.Org 7.4 release to come out shortly, along with a
number of other libraries and such that I've recently bumped.
Please test them and report any bugs you come across, along with `emerge
--info`, /var/log/Xorg.0.log and /etc/X11/xorg.conf.
Developer, Gentoo Linux