is about to release the next set of GPU programming documentation to aid in the development of the open-source R500/600 drivers for the xf86-video-ati and xf86-video-radeonhd.
The documentation will be NDA-free, but is unlikely to contain data on accelerated video playback.
On the RadeonHD IRC channel, AMD spokesman John Bridgman has stated that they'll be releasing IDCT (Inverse Discrete Cosine Transform) and MC (Motion Compensation) information for everything up to and including the Radeon X1000 "R500" series.
The IDCT/MC information can be used for hardware-assisted video decoding. However, it will not release information on the open-source video playback on the Radeon HD 2000 "R600" series.