Considering the source engine is being ported to mac (OpenGL) it's probably not far off from porting it to Linux considering the similarities between the systems. Under the hood i believe Mac OSX uses a BSD/Mach kernel hybrid, you can actually compile some linux sources for mac and have it work.
Maybe so but how many games that don't use Source use Steam though? To be honest the fact that Valve has decided to convert a 10 year old gaming engine to Linux isn't really world beating news. If you were suddenly gonna get better graphics, faster gameplay or more reliability then maybe just maybe it would be worth getting a semi on for but chances are it will be none of those things.
Uh, for starters the gaming engine is only 6 years old, and that's its oldest revision with Half Life 2. It has gone through many revisions since then with their latest titles. Not only does it bring in the base games, but the ability to play the mods available for the games. This isn't about exposing games to the linux community, it's about raising interest in the linux gaming community and opening doors for developers.
Yeah, Valve's "Source Engine" is one of the most played out there, PC wise. Most of the most popular PC shooters use a version of Valve's Engines. So it's a big deal for PC users - So yeah, it matters
