KMS - Kernel ModeSetting = the way the correct resolution is set up for specific screens. (when you change resolution, this handles it at hardware level)
Mesa - the (only) OSS implementation of OpenGL.
Gallium - a sort of layer between graphic cards and a graphics API. The graphic driver only has to 'support' gallium3D.
DRI - how software communicates with the hardware.
But do read the links posted by chithanh.
It's on its way. Michael gave us a useless preview. and BTW : nothing is stopping you from installing PTS and benchmarking yourselfA comparison between open source AMD and catalyst might be interesting. Their open source drivers aren't that slow to begin with. They might beat the blob, when performance doubles.
D3D9 for Gallium sounds really nice. Knowing the number of awesome games based on it, losing them would be a huge loss.
Right now a lot of people, including myself, don't use Linux because too many games run piss slow. I have a Linux machine sitting on the side, to see how the Linux world is doing. A 100% speed up of DX9 games would certainly make me want to install Linux as a primary OS on my PC. I personally couldn't care about DX10/DX11 at the moment.
Is there patent problems about DirectX ?
If not, and as most of the proprietary driver code is shared between operating systems, Nvidia and AMD just need to "enable it" for Linux builds ?
If the patch gets accepted by Wine and Mesa, and people begin to use it, it might be worth it for NVidia to enable it in their binary blob.
Right now it's so much easier and less error prone to just boot windows when you wanna play.... For many years nothing will change in Linux when it comes to games. Things are starting to move but it will take many years before we will be able to play windows games on Linux at similar performance.
Is a great year to be using open source drivers, a great year indeed.