To quote the Kingston Trio (a folk singing group) introducing one of their songs "Now in response to a diminishing number of requests" , here are a couple of threads that might be of interest to BluRay authors, particularly the part that demonstrate that about an hour's worth of HD content may be put onto a dual layer DVD disk.
http://forums.creativecow.net/thread/145/862674
http://dvinfo.net/conf/showthread.php?t=124190
John