Added 'Rumor' tag as it is coming from Michael Larabel of Phoronix and of course, nothing is official.
In 2010, Phoronix ran several articles claiming that Steam is officially coming to the Linux platform, but Valve denied it.
Fast forward 2 years and Valve have recently asked for Linux developers to iron out bugs and furthermore, invited Michael to Valve's HQ to discuss Valve and Linux.
That visit took place today and Michael has tweeted "steam is coming to Linux...". We are waiting for an article to be posted on Phoronix with screenshots and other goodies from the visit.
Is it true or not, I'm not sure due to the previous articles ran in 2010. But this time, it sounds far more realistic than before.