Intel's graphics research group has recreated levels in the latest Wolfenstein with added elements such as chandeliers, for the purpose of accurately portraying light refraction using ray casting. TL;DR? It's pretty damn impressive.
Using ray casting, reflected or refracted images in objects like the chandelier, a polished car, or surveillance screens are accurately shown in real-time. In fact, the demo maintains an impressive framerate the entire way through, despite the chandelier having over a million triangles.
This sort of tech isn't going to be under your Christmas tree in a few months, however. Intel are using the Knights Ferry kit, which at 32 x86 cores, is targeted at "computing segments such as exploration, scientific research and financial or climate simulation".
Although they are also making use of a tech the US will see soon, even if we won't. The four servers housing all those cores are connected to one little laptop, streaming the video - demonstrating that once this type of computing power hits the mainstream, cloud gaming will be ready for it.