Check it there:
Did not find new features since 3.1beta, just bug fixes. 2D surface write intrinsics that were buggy in 3.1 Beta are now working for instance.
There is also a reference to GPUDirect in the "release highlights", but I did not find any documentation for it. GPUDirect seams to allow third party devices to do direct memory acces to the GPU memory (cf the anouncement here).