The NVIDIA GT300 will be made on a 40nm process and will offer support for DirectX 11, additionally, it will also introduce CUDA 3.0.
Details about the GT300 are slim but the German site claims NVIDIA will start using Multiple Instruction Multiple Data (MIMD) units instead of Single Instruction Multiple Data (SIMD), which will result in more computing power. The clusters organisation will be more dynamic, there will be additional buffers and NVIDIA will use a crossbar for faster data communication.
Hardware-Infos further claims that the GT300 will feature radically different power and memory management. It's said that the GT200 was just an improved G80 with better GPGPU computing, while the GT300 will be the real successor of the G80.