It lets you use the GFX card to run code, its whats used in that Iray I posted up, big in research as its a huge increase in speed over the CPU (for some things) a guy I know has run a genetic algorithm that used to take 2 days on a CPU in about 2 mins on a SLI Gforce GPU (with some optimization of the base code).

The samples are superb to show the power. Volumetric particle smoke running with shadows, transprancy at 19fps, lots of particles at 150fps.

Well managed to get it going without buggering up my screen. Gonna code some simple matrix maths and see the difference.