There is indeed a new PSP that came out September 2007. Its called the PSP Slim and the hard drive is really only used for storing the system firmware unless of course you have hacked your PSP Slim in which case the internal flash memory can be used for other things such as installing custom firmware which allows you to run unsigned code such as custom themes (really cool btw), homebrew games/apps, and various plugins. Of course I would never do that to my PSP
. Other than that, memory sticks are used for storing your pictures, music, videos, etc. There are only a few things different between the PSP Slim and the original PSP (aka Phat PSP) such as a video output port that lets you connect the PSP to an external display, faster loading times, simpler tray for inserting the disks, along with a few other obsolete features.