Back before Christmas there was a rumour that there was going to be a "refresh the PlayStation Portable product line with a PSP-4000 model in late 2009 and launch a true successor - a PSP2."
Well, it's after Christmas now, and the rumour won't lie down and die. It has been reignited by a "highly trusted source" from somewhere (maybe Sony, maybe a publishers, maybe the chap who designed the image you see to the right - which is a mock-up) who has told VG247 that, "The revamp does have a sliding front-screen, and we’re assured the design being currently touted isn’t a million miles away from this now-infamous image."
The refresh will be announced at E3 or GDC... or somewhere, this year.