This is to track regressions which are caused by the upgrade to Mesa 10. If you encounter a regression, please do not comment here. Instead, file a separate bug and make it block this bug.
seem this start to bite, there are blocking involving sys-devel/llvm-3.4 and others. kmscon is fixed upstream, eselect-opengl is probably doing the wrong thing and patches are in the comments. Seamonkey is not IMHO important enough to block such an important package. There are other known problems not linked to this bug?
I've now removed the mesa-10.0 mask.
Mesa 10 has been in the tree and stable for a while.