That’s a huuuuuuggggge breakthrough and nudge to the lead in technology TDK shows 100GB! Blu-ray Disc . . . that’s 100Gig recordable while HD DVDs are up to 45 gigs read-only at the same point:

The Japanese Newspaper Nihon Keizai Shimbun Thursday morning edition reports that TDK pushes Sony’s Blu-ray format forward by announcing a 100GB recordable Blu-ray disc. Toshiba just proudly announced a HD DVD with 45GB capacity that was only read-only. The TDK 100GB recordable Blu-ray disc has 4 layers. TDK also doubled the writing speed compared to the 50GB Blu-ray disc. There is no information yet when the 100GB Blu-ray discs will hit the market. The talks between Toshiba and Sony on unifying the next generation formats have are still not leading anywhere in the meantime. Apparently now the presidents of Sony, Toshiba and Matsushita will meet to find a way to work together.

That’s a huge difference.