The methods to blend more nicely low rez buffers are pretty well known ,but i don't think PD could afford the extra cost.This one is big. I think its for the first time used in-game. Is there any chance for inside of the milliseconds GPU/CPU cost?
They should just phone to Polyphony and gave them this tech.
http://http.developer.nvidia.com/GPUGems3/gpugems3_ch23.html