For years there has been talk of Steam coming to Linux. They have been testing Ubuntu, one of the Linux operating systems, for a few source games over the last several years and have been met with success. The first game they successfully brought over to Linux was Left 4 Dead 2, but it had been a small team working on that. Since that success Valve got a bit more interested and have started some news projects, like getting Steam onto Linux with full functionality, getting L4D2 to run at a high frame rate on Ubuntu and porting more Valve titles. They chose to do all of this on Ubuntu because it is very popular among Linux users and good for gaming. All of that isn't huge news, but the most important thing to note is that Valve has set up a Valve Linux blog and will be updating that regularly with their progress. Keep an eye on it.
Valve Linux Blog: http://blogs.valvesoftware.com/linux/
-Written by Sean Cargle