PS2 HDD (40Gig) has been around in Japan for quite a while now. It was first used to run games like FF10 and Xenosaga from HD. Some people claimed that the loading time improved.
PS2 HDD is also a required component to play FF11. As far as I understand, the game DVD works as the installation DVD. Square has released bunch of patches since FF11 was released. There is also FF11 expansion pack (sounds too much like PC games, huh?).
There are two different versions-internal and external. Also I believe PS2 HDD comes with ethernet interface (called BB unit). But for some reason PS2 HDD unit's price is ridiculously expensive. It might be better to get the Linux development kit. For about the same price, it offers Linux disto designed for PS2, BB unit, keyboard and mouse.
It will be really nice if I can use my PS2 to record MD (currently moving between MP3 player (one from iRiver) and MD (probably N10)).
