This machine features not only the large primary heat sink, but also two smaller heat sinks.

Holy thermal paste! Time will tell if the gobs of thermal paste applied to the CPU and GPU will cause overheating issues down the road.

The Mid 2010 15" Unibody was equipped with only one large heat sink to cool just the CPU and GPU. Also for that revision, the graphics switching chip seen in the second image was present, but didn't receive a heat sink.

The chip under the heat sink in the third image is a new chip that is most likely the Thunderbolt controller.