Valve launches SteamOS

Supplemented with performance metrics (like the "Windows Experience" metric set in Vista and up) and feature presence tests, and you can automate compatibility by encouraging developers to put performance and feature requirements in package manifests. You might even go so far as to warn the user if they want to run a game for which their system is on the edge of supported specs.

It would help with things like "why is this game so sloow?" "You see that yellow marker next to the title? That means your system isn't fast enough to run that game at the visuals preferences you set in your global settings. Don't ignore that yellow marker."