yup, the PSP 3000 screen introduces scanlines and it's a pretty severe problem from the looks of everything I've read so far. To be fair though, I haven't seen one in person.
It's also nothing that can be "fixed" as its 100% a hardware issue. It also currently cannot be flashed as far as I know. Sony disabled the Pandora battery hack on the 3000 and has made some other minor changes that has stopped all hacking processes so far. My guess is the scene will get around that sooner rather than later, but it's not an option right now.
Personally if I needed another PSP, I'd look for a PSP Slim, model 2000.