Picked up a new GTX 770 so I felt the need to do some more GPU compute work. I had a go at computing some bounce lighting, this is what I've come up with so far. Its only one bounce and it takes about 24 hours to light 16384 X 16384 pixels. (Think I should stop blaming the hardware and write faster code). I think the sky maybe over influencing the final result. But we'll have to wait until I composite it in before we will know.