I can't cite my source but it was linked from macrumors. Basicly it has incrementally better audio treatment (allegedly) and a slightly different video treatment, which I am SURE a human could not detect the difference between.
Rocketman
Interesting, but totally off-base. Blu-ray suppports fully uncompressed audio. Additionally, the higher bitrates overall imparted by the better laser allow for higher quality data streams of all types.