Update: The app has been removed from the App Store, as spotted by Parker Ortolani. It’s unclear if the developer or Apple removed the app.
Apple changed the App Store rules last week to seemingly permit game emulators on the iPhone for the first time.
Following that policy change, the first emulator apps are now appearing on the store. iGBA is a free Game Boy game emulator for iPhone and iPad, which can indeed load and play ROMs downloaded to the device — a category of application that Apple would have unequivocally rejected a fortnight ago.