The latest cooling technique consists of rips that are filled with Butane gas. It has a heat conductivity that is many times higher than that of metals. This is called A.C.T. which means Aeronautical Cooling Technology.Here is a picture of the NV38 (GeForce 9950). Rumours go that this one has a core running at 500MHz, and memory running at 1000MHz :
Pictures of the backside of this card and pictures of the NV36 can be found here at THG