One of the biggest missing pieces in the free software desktop will increasingly become good OpenGL drivers.
Alas, it is easier to write user-space programs than it is to write drivers. A user-space program will simply work on all systems that support whatever libraries it uses (say the C library), where as with drivers, the API for each and every driver interface is vastly different.
I wish there were some clear solution to this issue....
There is, simply not supporting companies that refuse to give specifications to their hardware, and nagging them to release these specs. The OpenBSD community has been very sucessfull in this regard, and it is a bit of a shame that the GNU project, the FSF and FSFE have been a bit lacking.