These sorts of real-time raytracing videos seem to get posted from time
to time, but I nevertheless thought this one was a but cooler than
others I'd seen. Still not at a level where it's usable in a game, but
it looks like this possibility might not be too far off in the future:
http://www.youtube.com/watch?v=gZlCWLbwC-0
And one showing off a little bit of reflection and refraction:
http://www.youtube.com/watch?v=4zMSsRtItOg
