*"Surely it would be nice, we could add the GPU on a graphic card to the rendering process, since it's doing barely nothing at all, while the CPU is rendering at full power. But like discribed above, it won't be that easy, to stear and handle the data stream to and from those SMs and cores, because they are usually used for different, specialized stuff relating to realtime 3D.

Photoshop CS4 started to use GPU calculation in a few effects / features such as realtime zoom and rotating and a few other things ...

But since they are different and use a different technical architecture while processing data, like FrankT mentioned, it must be more complicated to add them to a rendering process, otherwise it would have been done already since a longer time ... doesn't matter if we are talking about Vue, or other well known expensive highend graphic packages like C4D, 3dsMax, Houdini and whatever they are called ..."*

GPU Render Engines are coming. See Octane Render (Demo at http://www.refractivesoftware.com/ which works excellently already ) an unbiased render engine running on Nvidia 8000 series GPU's and above. there's a GPU based render engine coming from the Vray boys in the next few months as well with several others in the pipeline.

the best part is, you can run these along side a CPU render engine....

interesting times ahead.... oh yes.