...A final iPhone 3GS jailbreak hasn't been released yet, but that isn't stopping enterprising hackers from trying to get at all that extra horsepower, and some of the first notable hacks we've seen are these updated PlayStation 1 and Game Boy Advance emulator ports, which run way faster

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http://www.engadget.com/2009/06/25/iphone-3gs-gets-playstation-game-boy-advance-emulators/