Big thanks to Telemmaite for mentioning this paper in the Cycles Tests thread. While looking at the research paper, I also found this video appended to the paper. NOTE: I didn’t make this video (as if anyone could think I was this clever!) It’s Fair Use. The video was created by Pradeep Sen’s team who did the research.
At any rate, although Lux was used to create the animation here, they apply the technique to an 8 sample (!) animation. Yet the finished animation is lovely. Were this to eventually come to Cycles, it could make Cycles animation quick, very production ready, and legendary.
Looking at the other topics in this forum, I realize I may have put it in the wrong forum. Sorry if I did.
Update: Before you start yelling, it turns out that Brecht (and it appears everyone else…) already knows about this, and many similar papers besides. While it’s an interesting technique, it also has it’s own drawbacks, as pointed out by Brecht a month ago…