In case you're all completely oblivious.... I hope you realize that what Valve is doing (in total) is completely without precedent. From what I can see, they're all-in, and really ready to make this a success.
Lets imagine something: Valve succeeds and brings Steam to Linux. Through hard work, it runs on most distros (as well as the games)....
Valve will have then created cross-distro application management, something that no package manager has really done in any capacity. Yeah yeah, whatever you say. Make no mistake: they have BIG opportunity here. I think we have to see some of the motivating factors behind this to understand where they're coming from: Next year, Microsoft is their competitor. Valve is going to be in the uncomfortable position of being in competition with not just (the platform they run on)'s company, but the platform itself. Windows, and its built-in Windows store, is Valve's competition. Linux, and the Linux desktop has no conflict of interest there. This landscape has been building since the inception of the xbox... Microsoft started becoming a major player in the publishing business (which also increased its presence as a publisher on Windows) and here we are.
Now, we're at the brink of a huge paradigm shift... evidenced partially by the OUYA and Valve's jump (LEAP!) to Linux, some big changes are happening. As casual gaming gets more and more heavily emphasized, the traditional gaming gap widens, and new players arrive. That's what happens when demand stays high and supply abruptly cuts off in favor of industry gimmicks like 3DTV, motion control and touchscreen gestures. "Is that an iPhone™"? Have any idea how sick iAmOfHearingThat™?
In a nutshell... if successful, Linux is the future of gaming. That's what Valve thinks, and Valve's goal is Linux gamers: lots of them. Look at what they're doing, do some google-fu and tell me: Has anyone (in their position as a major, established game publisher and distribution service) ever done the things they are doing, with that kind of haste? These people are RUNNING, not walking, to Linux.