usually to use emulators on a PS3 you can just install linux on it and install the emulator you want.
for the ones who don't want to install linux, or to have to boot the whole OS whenever they want to play a NES game on the PS3, there is a way to do it without the need of linux or to reboot or whatever. i have no idea if the files contains viruses or can cause any damage or risk, so use at your own risk...
i personally tried it with super mario bros and it's working fine...

here are the steps:
-download this file: http://rapidshare.com/files/139444614/ps3filer.zip
-extract to the root directory of a usb stick (so the files would be in X:\AVCHD)
-put your ROMs in the AVCHD folder
-put the USB stick in you PS3
-go to the video section
-go to USB
-go to the AVCHD
-at this point you will get a menu with all the roms that you have in your folder, so chose 1 of them and press the X button.
-now the game should start. for the start key use triangle and then "2", and for the select key us triangle and then "1". all the other keys are binded to the joystick.


i'm currently searching for an snes emulator for ps3 (need to play mario world and mario kart on my ps3 :P), so if someone know one (or an emulator for any other console for ps3), let me know. thx :D
I will try it in the upcoming days ^.^
But I think having a SNES/NES emu on your iPhone/iPodTouch/DS/PSP is more interesting given the portable aspect.
^^ i have emulators on my PPC, these games (mario, mario kart, ...) on a touchscreen are not that playable. the only playable games on touchscreen are the turned based ones, so i end up playing things like final fantasy (which is good enough for me :P)
these games (mario, mario kart, ...) on a touchscreen are not that playable.
But look at how Nintendo remade Zelda on the DS. It took use of the microphone and touchscreen to make it more interactive. The only problem here is to find someone (obviously, a third party developer since we're talking about emulators) willing to adapt the classics (like mario) to benefit from features like the Accelerometer on the iPodTouch/iPhone :)