No, I'm running Windows x64, so it's possible that Linux drivers don't have the same problem. I was being somewhat facetious, but the fact is that I can't run any nVidia driver after 314.22 on my system for more than a few days without occasional temporary freezes and some that require a cold restart. This isn't an isolated complaint. They have a bug, somewhere, that's been there for a few months now.
I see, I would point out that for production work you are very unlikely to be running the latest release of any video driver due to it being largely untested in the wild, no matter if you run Linux or Windows.
So the official SteamBox will come with very stable drivers for it's hardware configuration, and the same goes for third-party 'Steamboxes' aswell I'm sure.
For Steam users running on their own machine configurations it's another thing of course, but that's no different from the way PC gaming has always been.
One possible difference is that the official Steambox will likely function as a 'confirmed' hardware configuration so even if you 'build you own machine' or look to buy another offering you can use the hardware setup of of existing Steambox(es) as a hint of what to buy for the best 'Steam-experience'.
Anyway the reason NVidia has had strong Linux driver support for such a long time has nothing to do with desktop Linux and certainly not Linux gaming.
It's because Linux is huge in 3d and special effects (mainly movie, tv) and of course dominant in hpc.
However, Steambox is likely resulting in NVidia improving their Linux video drivers with focus on game performance.