For some reason opengl-update-1.8 has xorg-6.7.0-r2 as a dependency. This is a problem for people like me, who want to use the latest nvidia drivers but still use XFree. There is no explanation in either the ebuild or the changelog as to why the xorg dependency has been added...
Take a look at this bug #54984
It has been removed as of about 12 hours ago. Please resync your tree. But be aware you will need to do a userspace fix instructions are in the ebuild
Fixed.