cburke82, my understanding is you can build your own machine and have Steam OS installed on it, like fatelost said. There's nothing really special about it other than it's an alternative OS. That also means games must be especially designed to run on Steam OS.
That said I know of 2 guys personally who will be uninstalling Windows from their machines and turning them into Steam OS boxes that can dual boot with Linux. They know there will be games they can't play right now, or maybe ever, but their hatred of Microsoft and therefore Windows is greater than their love of those games.