Valve has muttered and murmured about bringing Steam and its Source engine to Linux before, and now it's revealed the plan--port Steam and Left 4 Dead 2 to Ubuntu 12.04, then work from there. Steam will come to Linux in all its glory, and Valve's building a speedy OpenGL version of Source it can use for more of its games too.
The Valve Linux Team already has Steam and L4D2 up and running natively on Ubuntu, the 11-person group formed in 2011 explains in its first blog post. They need a bit more work before we can all play with them, though, and Valve notes, "Our goal is to have L4D2 performing under Linux as well as it performs under Windows."
Why Ubuntu? The team explains, "First, we're just starting development and working with a single distribution is critical when you are experimenting, as we are. It reduces the variability of the testing space and makes early iteration easier and faster. Secondly, Ubuntu is a popular distribution and has recognition with the general gaming and developer communities."
Depending on how well it goes down, the team will look at bringing Steam to more distros. And, naturally, Valve wants to bring more of its games to Linux.
Linux users have enthusiastically supported efforts to bring proper games to its platform (sorry, Tux Racer), consistently paying far more to the Humble Bundles than Mac and Windows folks.