The second issue is with the driver subsystem. The kernel developers need either a) stop breaking the existing driver interface ever other release or b) create new modern interface that's stable like MS did with Vista.
Imagine if every windows update, you had to worry about you games not working because MS might break the drivers. This is how Linux is now. This situation is especially bad for users with old and very new cards. For example, my X1900 can't run the catalyst drivers with any modern kernel, making it useless in Linux as my spare gaming rig. Of course it works perfectly in Win7, running about 2-5x faster than the worthless, buggy, open source drivers.
Fixing the video driver subsystem is exactly the kind dedication that would prove to me that Value is serious about making Linux a competitive gaming platform and likely convince me to purchase a SteamMachine.
AMD have been shit since forever. There should be a message with giant letters printed on each box saying "THIS PRODUCT DOESN'T HAVE LINUX DRIVERS WORTH A DAMN".
Not that it helps your situation now, but maybe if you upgrade in the future, try with an nvidia card?
By helping out the FOSS community to have better OpenGL driver support it will get Valve Software a lot of goodwill. Projects like Dolphin will benefit from it, and of course those Steam Linux games will as well.
I really want to see the Linux Gaming Platform take off, many game developers avoid Linux ports because of buggy OpenGL drivers and bad support of it. I think Microsoft did this with DirectX standards because I remember early on DirectX drivers were buggy and game companies wanted to stay with DOS based games and not port to Windows, because DOS had better video support drivers. Once Microsoft worked with video card OEMs to improve their drivers and DirectX support, the video game companies ported their games to Windows 32 bit format (Windows 9X and then later NT/2000/XP) because of DirectX based libraries and better drivers and fewer bugs. It will take a company like Valve to coordinate the OpenGL stability between OEMs to get it stable enough to port games to Linux.