Simple question: if Valve employees are so eager and willing to share their supposed Linux plans with every chap who's able to peruse an e-mail client, and let them blare this information into the world, why then is there nothing official or at least semi-official? There's a big Linux thread at the Steam Users' Forums, where people are asking all the same questions. Nobody from Valve provides answers there. No renowned gaming website has picked up on this. And it's their frakkin' job to report "rumors".
If you want Steam on Linux, it's easier to take a dump on your computer than to wait for the prophecies of conspiracy theorists to become true.