Toshiba is currently drafting a new breed of HD DVD discs which should top Blu-Ray’s maximum capacity barrier by one gigabyte (totalling 51GB of space) – hence removing the claim that HD DVD is inferior to Blu-Ray, capacity-wise. It will incorporate three (3) layers, 17 gigs each. Toshiba claims this disc could hold up to seven (7) hours of high definition video.

It’s not sure if this disc will be backwards compatible with the older generation of HD DVDs.

Source

ArsTechnica: http://arstechnica.com/news.ars/post/20070116-8628.html
Digg story: http://digg.com/tech_news/High_capacity_HD_DVD_disc