It's been confirmed, and yes I am aware of the 2010 "claim" too. You will see when I post links why they weren't wrong then either:
References of Steam Linux confirmation:
http://www.phoronix.com/scan.php?page=a ... deln&num=1(This next one features Jono Bacon from Canonical, makers of Ubuntu Linux:)
https://www.youtube.com/watch?v=5-SmNPj ... ge#t=3134s(This next one isn't very good quality, but the process is listed there)
http://www.youtube.com/watch?v=t_sLKHOHtug(This next one is from this Reddit user post:
http://www.reddit.com/r/linux_gaming/co ... x_youtube/ Three posts down)
http://i.imgur.com/UeQIf.jpg(This next one is the author of the first article on IRC, where he mentions Gabe N bashing Windows harder than he does:)
http://pastebin.com/RSxVqgJBNow, I do realise things like an IRC paste isn't "proof", I also realise that some people havn't any faith in Phoronix, but do understand there are more links to what Gabe actually said. I will post them if I find them again - right now there is much "Steam coming to Linux" on the net, it's hard to sift through what I saw where. But it is all there on the Interwebz,
www.reddit.com is a good place to look. Specifically,
http://www.reddit.com/r/linux_gamingBut Steam IS coming to Linux, very soon, whether you believe it or not. However, if you don't believe it, that's fine, but do expect an "I TOLD YOU SO!" soon in this thread, when Steam for Linux is released

And it all makes sense. Disregard Gabe Newell's thoughts on Windows 8, the Win 8 App Store alone will steal market share from Steam. Apple has one now, and as well as a bunch of other things, it really does make sense for Valve to release a Linux client of Steam. Everyone else seem's to share this opinion too. Now, I'm not going to really get into why Runic can or cannot release a Linux client for Torchlight 2. But I will say the fact is that much smaller studios release Linux games, and now, much bigger studios release Linux games (Valve). So........discuss it, if you want. I'm not sure if I'll say much more on Runic and Linux.