basically it's a way of pirating (sorry, 'ripping') TrueHD and DTS-HD Master Audio into a non-DRM format.
essentially you have bit perfect audio that can be played by the majority of software players out there.
it also bypasses the 48kHz/16bit downmix for ATI HDMI LPCM audio when playing from a bluray disc. giving you the original sample rate and bit depth.
no current standalones support it as far as i know.