The "employment opportunities" section in their website is the new source of all the hype. The responsibilities of the desired candidate for the post of Senior Software Engineer include "Port Windows-based games to the Linux platform".
What else do you need for another round of controversy. It seems that, the notice have been there for sometime which clearly shows Valve is indeed interested in bringing their products to Linux. As somebody have commented in the reddit thread, I can sum up the whole thing in one sentence, "I WANT TO BELIEVE!!" Let's hope, our cries are heard this time at least.