Valve bringing Steam to Linux?

Phoronix's Michael Larabel posted a write-up yesterday detailing fresh Linux code buried in the bash script launcher for the Mac version of Steam, currently in closed beta testing. Here's the script and Phoronix's original article here.

Logically, if a Linux Steam client exists, then a Linux version of Valve's award-winning Source engine would also have to exist, as Source is required to run all of Valve's games.
At this point, it's all speculation. Phoronix has several articles from years past that claim the existence of Steam and/or Source, based on job announcements, unnamed sources, and Linux code found in the Left 4 Dead demo.

Still, the inclusion of Linux in Steam's platform would usher in a wealth of native-running, critically acclaimed games, even if the only titles available would come directly from Valve. For now, Linux adopters hoping to survive Left 4 Dead 2 or wrap their minds around Portal will have to do so through a Windows emulator.