As far as I know, a PSP emulator does exist but it;s still very much rudimentry. Just can play a home brew games and that's all. Ripped game UMD's are available freely on the net but the emulator hasn't been able to play them...yet. The only fully functional emulator can be found with Sony itself, but for that you will have to be a game dev yourself or a really fanatic cracker ready to have your ass sued to kingdom come by Sony.