Got a nice email when i just got home with a new emulator for the PSP, the emulator is an Atari 2600 emulator for the PSP which is a port of the rather great Stella Atari2600 emulator. The coder who ported it is called Aenea, heres whats in the readme:
This is a port of the Stella Atari 2600 emulator to the PSP. Original code by Bradford W. Mott, Stephen Anthony and Jeff Miller and many others. This PSP port was made by Alysa Habraken (aka Aenea). It's not very optimized and not all games run or at full speed. Some have a little flickering, but this will be resolved in upcoming versions.
Heres some shots
Ive made a v1.0 eboot and stuck it in the Zip and also you must read the instructions ive posted to get it to recognise roms