Valve claim that Steam is not coming to Linux despite earlier reports suggesting that it will.
The rumours originated from Phoronix - which seemed promising, but Valve stayed quiet about it. However, Valve recently confirmed a Linux version is not being worked on.
To quote Valve from the GamesIndustry.biz interview:
QuoteQuestion: Final question, and one I'm sure you're not super-keen to answer, but I promised one of our tech guys I'd ask it. What truth is there to rumours that you're also working on a Linux version of Steam?
Doug Lombardi: There's no Linux version that we're working on right now.
Hopefully it will eventually!