Fuad from The Inquirer is reporting that NVIDIA's upcoming G80 GPU will be DX10 compliant, but that it won't feature a unified shader architecture. Rumor has is ATI's R600 GPU will be a unified architecture, however, leveraging technology introduced from the chip used in the XBox360. Details about either GPU at this point in time should be taken with a grain of salt. Regardless, it's always fun to speculate and get a hint at what today's graphic's giants are working on.
"AS we understand it, if a Nvidia DX10 chip ends up with 32 pixel-Shaders, the same chip will have 16 Shaders that will be able to process geometry instancing or the vertex information.
ATI's R600 and its unified Shaders work a bit differently. Let's assume that ATI hardware has 64 unified Shaders. This means that ATI can process 64 pixel lines only per clock. That may be in the proportions: 50 pixel, 14 vertex and geometry lines per clock, or 40 vertex, 10 pixel and 14 geometry information per clock. Any ratio that adds up to 64 will do. I hope you get this maths."