The mesa libraries in app-emulation/emul-linux-x86-opengl-20130224 only support OpenGL 2.1. Recent versions of mesa introduce OpenGL 3.0 support, which is needed by various games. In particular, games installed by Steam, Wine and Crossover link against the 32-bit libraries and the lack of OpenGL 3.0 support significantly reduces the number of titles that can be played.
This version has mesa-9.0.1, and while it isn't the absolute newest mesa available, it does support up to opengl-3.1 on some drivers like i965. Another bump to these libs would still be great, but the current version is not as bad as the summary suggests, just FYI.
9.1.6 was included