HD-DVD has already dual layer. BR's DL has just arrived with Click... but whether or not the entire movie is spread across both discs is unknown. could be movie on 1 layer and features on the other. i think Kingdom of Heaven will be the true test =).
wow! How can this be? I figure the reason for layer chage being un-noticeable is that there is a big enough buffer to "cover" for the delay to switch layers. Wouldn't there be LESS to buffer on an SD-DVD therefore making it EASIER to cover?