Early progress on porting Siri to the iPad has been made by jackoplane, reports JaibreakStory.
Jack’s Siri on the iPad 1 isn’t communicating with the Apple servers but as @stroughtonsmith told us, any iOS device could be spoofed to look like an iPhone 4S and communicate with Apple’s servers. If nothing works, Siri’s interface could be used to query google or TellMe.
For now, it seems that @jackoplane has a full working Siri with the iPhone 4, hopefully we have good news for the 3GS and the iPad 1. Porting Siri to any device other than the iPhone 4S will require a jailbreak for the iPhone 4S device itself to be able to move data from it to other devices.