In an interview with EDGE Magazine, Christophe Balestra, Naughty Dog co-president, said “Uncharted used 30 per cent of the PS3’s SPUs, and this time we’re maxing it out,” he said. “That means we can blend and switch animations a lot quicker, and we have more facial joints in-game for characters to react with believable expressions.” In order to use the full power of the PS3, Naughty Dog shifted processes from the main processor and shifted them onto the SPUs.
Amy Hennig from Naughty Dog also revealed similar details in an interview with GameTrailers at PAX. The result is incredibly brilliant graphics and animations.