AMD's upcoming ATI RV870 GPU is codenamed "Lil Dragon" and according to Nordic Hardware this 40nm shrink of the RV770 (Radeon HD 4800 series) will offer twice as much performance per Watt than its predecessor.
The ATI RV870 GPU is expected in the first quarter of 2009 and according to the report it will be about 20 percent faster than the RV770 but it should offer big drops in power consumption.
The overall performance has been suggested to be somewhere around 20% better than RV770 with a significant drop in power consumption. This points to 960 shaders (192x5), 48 texture units, 24 ROPs and so forth. If this is the case, TDP of the RV870 should be around 150W at most with today's frequencies. This is just an estimate on our part as technical specifications are still hard to come by. We also presume AMD to stay at DirectX 10.1 for now.