If your love for snes and nes gaming on the iPhone or iPod touch is restricted by the price you need to pay for the emulators, xsellize has the cracked version for you completely free of cost. snes4iphone and nes4iphone are now available on xsellize, check here to get xsellize source on your iPhone / iPod touch.
To get these emulators working you will need to get the snes and nes roms aswell. You can get them here. The controls and gaming look a bit sluggish, but thats probably I use a 2G iPhone.