There were rumours a while ago that Valve was working on Linux support for their infamous source engine which powers most if not all their games. What if it wasn't just support for linux but Steam running on a Valve tailored Linux kernel. Obviously most games would still need Windows for DirectX but all of Valves games and many others could work on this super thin Linux kernel.
* http://www.phoronix.com/scan.php?page=news_item&px=ODE4M...