Yes, I know about the PTX_ISA PDF… It is not meant as any hardware description. In one of the first pages, it already talks about a ‘virtual machine’. It is meant as a generic description of current and future NVidia computing devices. Did you notice it contains more things that aren’t actually implemented? One example is the .surface memory space. AFAIK, it does not exist for G80.
Any of the real hardware descriptions (like in the CUDA developer guide) does not mention local memory cache. So you cannot assume local memory is actually cached. Some experiments and timings have also shown that local memory is slow. Also, explicitly making things local was deprecated in 1.0. Try to stay clear from it as much as possible.