I do give Sony a lot of credit for using an OLED screen, but Samsung has AMOLED which offer better clarity and color reproduction. Sammy is having trouble producing enough of them for their own products, but I'm surprised Nintendo didn't use some fancy, super-clear, screens for the 3DS (like retina display, SuperLCD, etc.) and Sony didn't come out with their own screens for the new PSP devices.
Also, Sony, like everyone else is playing wait and see with the 3DS just like they did with the Wiis motion controls. If the 3DS ends up giving everyone headaches (I'm sure they tested long game sessions with their focus groups) Sony can sit back and laugh and market the PSP2 as a headache free device, which they may do anyway. It would be a lie (potentially) but it would make people doubt, and that's often enough.