NVIDIA developers are extending the "Video Decode and Presentation API for Unix" interfaces to allow the HEVC/H.265 requirements. The work aims to enable hardware-accelerated decoding of HEVC content under VDPAU and to provide a reference implementation for this video decoding. José Hiram Soltren, the developer that worked on this support, is also working on a HEVC decode patch for FFmpeg and MPlayer based upon the new API.
Those wishing to learn more about this HEVC/H.265 video decoding work for VDPAU can be found via this mailing list post. Of course, this is just for the public VDPAU library portion and is still dependent upon NVIDIA's binary driver support and on the open-source side within the VDPAU Gallium3D state tracker. As for hardware requirements, it's expected newer NVIDIA Maxwell GPUs should support H.265.