About Blu-ray Disc
Blu-ray Disc is a next-generation optical disc format being developed for High Definition video and high-capacity software applications. A single-layer Blu-ray Disc will hold up to 25 gigabytes of data and a double-layer Blu-ray Disc will hold up to 50 gigabytes of data...
If it's as good as it sounds this will be great. Read more at http://www.apple.com/pr/library/2005/mar/10blu-ray.html