Just to let you know HD-DVD media has been made, its just not made public because there is know public drive that will burn to it. HD-DVD come in dual layer, double sided dual layer (Signle layer on one side dual on the other), and triple layer technology. Don't believe me ... READ!
OH I know that. Just like how blu-ray discs have been made as well. They're on sale in Japan and run about $5000 just like HD-DVD players as well. However what Sony & Toshiba are trying to avoid is another format war like VHS and Betamax from way back when. As it looks, it seems that DVD a.ssociation will combine the 2 together; Using sonys blu-ray technology while using toshibas compression for more durable discs so they will not be encased in those thin plastic cartidges like PSP games are.