Really impressive stuff. In the video above Steam is being run somewhere in the cloud and streamed to the client which is Firefox. Rendering via ORBX.js and WebGL. Specs are impressive too:
25% better compression than H.264 for competitive quality, adaptive bit-rate while streaming, integer and (soon) floating point coding, better color depth, better intra-frame coding, a more parallelizable design — the list goes on.
Reminds me of a few existing ActiveX plugins for IE, such as the one by VMWare to accessing your remote machines from within the browser.
(via De Wasstraat #28)