I read Gabe's opinion about Win8 and Linux, but I didn't think he was in the works to port the source engine. Good on them. As for the benchmarks, meh ;p I think the important thing is that Valve is adopting OpenGL and other platforms. Whether or not people will adopt it solely on the presence of more games is debatable. I love developing for Linux and using it for some things, but it has a lot of hurdles to overcome if it is to become a viable alternative to the average Joe. It's a question of whether to improve Linux or improve the technical literacy of the general public Novell tried to pull that stunt back in 2K and it backfired.
Still, this will be interesting to see where it goes. I'm not crazy for Win 8 since I'm quite content with 7, but it will be interesting in the next couple of years where things go. With C++ and OpenGL, you open up PC Windows, Linux, Mac OS, iOS, and Android. With C++ DX you have Windows, XBox, and Win Phone, the later which hasn't shown a lot of promise yet (sadly). If Android and iOS secure their future as market leaders, pushing Windows mobile out, then that too will be a factor, I think, when people decide which APIs to use. The game is afoot. Let the GL vs DX wars commence