Marino, rendering is not my area of expertise, but being able to specify the number of rendering threads would be very cool for multi-processor systems. Now days, just about every new computer is at least dual core. This would make it more feasible for modelers to make more detailed models. I also don't know how this ties into the driver where it's actually telling the video chipset to do the rendering (or part of it) and it has a limited number of GPU cores, pipelines, or whatever, but it seems like a lot of this rendering is happening on the CPU (at least on my crappy laptop).
On the flip side of that, what would you think about a frame count cap, so that it doesn't attempt to render more than x frames per second.