As we mentioned in our earlier coverage, Siri was initially developed outside Apple at the SRI, and the original Siri app worked just fine on an iPhone 4, although it was never integrated the way it is in iOS 5. It is fair to say that the lack of Siri support on iPhone 4 is probably a way for Apple to differentiate the iPhone 4S from the iPhone 4.
Steven Troughton-Smith has been able to backport Siri from the iPhone 4S to the iPhone 4, and it means that iPhone 4 owners may be able to get Siri, at least for those who are willing to jailbreak (bypass Apple’s app install authorization) their phones.
So, does it work? It apparently does according to that movie and story from 9to5Mac, and the author even says that if it appears sluggish, it’s because there is a missing driver. Until then, we won’t know for sure how fast Siri really is on the iPhone 4. Obviously, the iPhone 4S has more muscles, there’s no question about it, but it would have been really nice if iPhone 4 users had access to Siri. Now, will Apple block it at the server level? Let’s wait and see!