
I am rendering right now this scene:

VirtualRender http://virtualrender.trueart.eu
can resume previously stopped or crashed for any reason

And what was rendered already, ready regions, remain on disk!
It's useful thing - you have one machine, render when you're outside or busy other not computer related things, and stop rendering still or animation, when you want to use computer without slow downs.
I have feeling that rendering Kray in VirtualRender is little faster than regular Kray. Current theory for this is that rendered region is whole in CPU cache L2 memory.