Siri

Siri is a voice assistant feature of the iPhone 4S and one of the main selling points for this device, although still in beta. A port to iPhone 4 and late model iPod touch has been completed by with the help of chpwn.

Files
Siri is am integral part of iOS 5 for the iPhone4S. Files include:

System/Library/PrivateFrameworks/AssistantServices.framework System/Library/PrivateFrameworks/AssistantUI.framework System/Library/CoreServices/Springboard.app/Assistant*

An additional key in the capabilities section of System/Library/CoreServices/Springboard.app/NxxAP.plist assistant