I just heard the 40GB Hard Drive has finally been released in Japan. Looks like it will be avaiable in the us in November. What it does. Of course it has the ability to store data on the Hard Drive, but the neat thing about it is the ability to temporarily place data on the Hard drives cach. ie it cuts down the load time for some upcoming games in the future. Developers will be making Hard Drive compatible games soon. (example Finial Fantasy X). Not sure what the cost will be.