Following our exclusive looks at the Siri port to the iPhone 4, developer Ryan Petrich¬†(with help from Steven Troughton-Smith and chpwn) has ported the Siri artificial-intelligence system to the iPhone 3GS. The port seems to work well based on the video, but we’ve been told that the microphone performance is significantly worse than the iPhone 4 microphone’s performance. If there is any significant ambient noise, the home button needs to be clicked to stop voice input.