Valve announced
SteamOS, an open-source, freeware Linux operating system that allows access to the entire Valve library (as well as games on LAN-connected PCs) on TV-connected PCs.
I'm really thinking the main driver is some sort of GPU-driven session virtualization, a la RemoteFX but presumably with client-side processing. I can't imagine they've found a seamless way to get Windows binaries and DirectX working for any and
every game using translators, so a pure WINE-type approach seems unlikely. Pure screen-streaming doesn't seem to fully explain it, either, particularly for the local game streaming. It's got to be streaming the screen for some games, I figure, but somehow offloading more of the work to the local hardware than we'd see in Xen or RDSH. It seems to be a lot more than just "streaming" games, though, so I'm sure it mixes native or translated support for local games.
This pure speculation, however. The announcement leaves room for little but guesswork. Clearly, they've made some big technical accomplishments in-house. I don't know if I'll even use this, myself, but I'm extremely curious to know the details of what they've accomplished. Maybe, just maybe it's big enough to excuse turning Half-Life into vaporware.