We are keeping track of SmallLuxGPU, a demo to use GPU rendering for Luxrender done by David Bucciarelli. SmallLuxGPU is a part of LuxRays, a module of Luxrender for accelerating the ray intersection processes using GPUs. Here are some recent demos. The first one is from David himself. There are also 2 nice videos from Phymec plus a newbie's guide to SmallLuxGPU for OSX from Sebastian König.
The video above is from David Bucciarelli, showing interactive material editing and also its almost real-time camera changing of Andrew Price's an Audi R8 scene.
Here are 2 videos from Phymec's youtube channel rendered with SmallLuxGPU v1.5, using Bullet Physics engine.
Update: Plus a very nice HD one, also from Phymec (Thanks to Jens for the link)
And the last video, "A newbie's guide to SmallLuxGPU for OSX" from Sebastian König, is a very introduction to start playing around with SmallLuxGPU on Mac OSX