SmallLuxGPU is a LuxRays (luxrender.net/wiki/index.php?title=LuxRays) demo and a LuxRender v0.8 "proof of concept" (luxrender.net/wiki/index.php?title=Luxrender_and_OpenCL).
Real-time sequences were recorded on a i7 860 + HD5870 + HD5850 at the resolution of 800x450. Off-line sequences were rendered with a i7 860 + HD5870 + HD5850 at the resolution of 1280x720.
SmallLuxGPU and LuxRays are released under GPL license and the sources are available here src.luxrender.net/luxrays/. Precompiled binaries are available on LuxRender forums (check the section dedicated to GPU acceleration).