I added the question mark because Valve hasn't announced it officially, however I suggest you read all of these articles here.
[Phoronix] Valve Updates Its Unreleased Steam Linux Client
[Phoronix] There Is No Doubt, Steam Is Coming To Linux!
[Phoronix] Proof In Steam's Mac Client Of Linux Support
Good news
[Phoronix] Valve Updates Its Unreleased Steam Linux Client
[Phoronix] There Is No Doubt, Steam Is Coming To Linux!
[Phoronix] Proof In Steam's Mac Client Of Linux Support
Good news