Kotaku just posted some interesting (rumoured) details about the new PSP due out later this year. Sony have said a number of times now that a redesigned PSP (with the same hardware) is in the works but not yet announced any official details. I'm going to shamelessly rip the article right here and now:
Keep in mind this isn't Playstation Portable 2, but rather a redesign of the original, so it will be sporting the same internal hardware. But that's about the only thing that hasn't changed. The new Playstation Portable will have a much slimmer design, thanks mostly to a new LED screen that will deliver an ultra-crisp image but take up far less space. That LED also helps pump up the battery life of this sexy new model, which can last as much as four times longer than the original PSP. While the new PSP still makes use of the UMD drive, it will be a faster version and to help speed up loadtimes and gameplay, the portable will come packed with 8GBs of internal flash memory. Finally, the PSP's much maligned buttons have been revamped and the D-Pad has gotten a major overhaul, giving portable gamers something more like a Playstation 3 D-pad to play with.
So that's quite nice then.