I posted a demo of the new Arauna2 renderer on ompf2.com:
A youtube of the demo can be found here:
A higher quality version of the video can be downloaded as well (warning: large; 850Mb):
And finally, the demo, which requires a decent CUDA device and 64-bit windows:
Arauna2 is an interactive path tracer, which produces images using a random process. As a result, images contain noise, which will fade away as the pixel values approach the 'expected value'. Arauna2 has been optimized to produce decent quality images very quickly, and converges to high quality images in seconds. It is intended for architectural walkthroughs, but something involving games would be even more awesome. As you can see in the demo, we are not there yet, sadly.
I believe Arauna2 is currently the fastest path tracer, but that is of course strongly dependent on requirements. Main limitation is the fixed shading path, which supports the full Phong model, specular, dielectrics, textures, normal mapping and emissive surfaces, as well as every sensible combination of those. Illumination is provided using light emitting surfaces, meshes, point lights, spotlights (including IES profile support) and directional lights.