Valve is moving Steam
to Linux, with their first port being Left 4 Dead 2. They will be moving the program to Ubuntu 12.04, a distribution of Liunx, based on Ubuntu's prior success.
The team at Valve is working now to provide a high frame rate for L4D2, as well as improved graphics. The company hopes to utilize more than just Ubuntu in the future, and fully expects to branch out even more.
The project is known as "Steam'd Penguins," and Valve will update their blog periodically for news on the program.