The GeForce GTX 560 should be launched next year and will replace the current GeForce GTX 460. The GF104 GPU has 8 SMs for a total of 384 shader processors (or SP). But like for the GTX 480, the GTX 460 has only 336 SP because one SM (=48 SP) is disabled.
The GF114 (GTX 560) GPU will do the same thing than the GF110: all SM will be enabled and then the GTX 560 will have 384 SP. Actually this is not a big surprise because NVIDIA has seriously improved the GF11x design compared to the GF10x one. That’s why the GTX 580 / GF110 is a full GF100 and that’s why the GF114 will be a full GF104.