From Gamepro "Ask the pros":
"Valcore: A while ago you posted a response to the question about needing Blu-ray for gaming. After seeing games like MotorStorm which took up 16GB of space and loose talk about Metal Gear Solid 4 filling up 50GB, has your opinion changed or do you still feel that its not necessary?
Mr. Marbles: Hey Valcore. While this was no doubt a long time ago, I don't remember saying we don't need Blu-ray, but I probably said that we're not ready for it yet.
I still feel that Blu-ray is not an absolute necessity for gaming at this current stage, though it will be within the next few years. There's no denying that Xbox 360 DVD-9 games like Gears of War can produce huge, beautiful gaming experiences, but as technology becomes more advanced, the amount of data on discs will definitely increase. Hence, Blu-ray is a big plus for Sony developers..."