Wouldn't be allowed in the app store, and good luck getting a license for the ROMs so it would be. Namco would be all 'You want to compete with our official iPhone ports? Goodbye'. There's a MAME port for jailbroken phones (someone recently accused MAMEdev of trying to sue it, something MAMEdev was surprised to hear about), but as with many games ported to the iPhone instead of designed for it the control experience is not great.