[cookiecaper]

There are actually some pretty decent alternatives on Linux, most obviously distro package management, some of which is now a platform for proprietary software too, but there are other competitors. Additionally, Steam works great with WINE and most Linux gamers use it without issue -- the main benefit from a native version would be inclusion in package managers or first-class distribution as a pre-installed app in e.g. Ubuntu or "Ubuntu's Gamer's Edition" or something like that.

I see no reason to infer that Newell's comments are limited specifically to app platforms. I also wouldn't be surprised if there's more to this than just a Steam-for-Linux download; they could be working on something like the old Phantom project to really bridge the gap between console and PC, and take advantage of Windows 8's almost inevitable initial poor reception to gain marketshare.