There's that (much of what you just summarized was covered by the SteamOS announcement Monday) and that today they announced next to nothing. Just a beta program for hardware that they'll have in a beta format sometime in the next few months, for a reference design in 2014. It's like they weren't ready to announce this, but had to so it wouldn't be caught in the harsh glare of all the next gen console PR that's going to go into heavy rotation shortly.
I'm interested in the ability to stream from my windows PC to my living room with a simple solution, something like NVidia's Shield product w/ a Chromecast or Roku form factor. Beyond that I'm not sure there's anything else that can really wow me. A new take on PC controllers? The PS4 probably has that covered (with the added bonus of working on one of my consoles). New engine and L4D3, or HL3? Time constraints limit my excitement over an engine or a single title these days. Probably also get a vague 2014 'if it's ready' tossed it's general direction too.