Originally Posted by Nightshade

HD DVDs use an encoding system that is a bit more than a regular DVD it uses a hexidecimal system. The theory has been held that one key code can crack it and enable ripping and copying of any and all discs without having to use individual keys (the usual way).

Well they found the key and made it public. Needless to say anyone who carries the key may face legal issues from the MPAA for having it published.