Just as it was for video recording, available for iPhone 3GS but not for iPhone 3G, even in the case of SIRI Apple has created a bad mood among its users, making the personal assistant available only for iPhone 4S and not for iPhone 4.
Disappointed iPhone 4 owners may have a faint hope to stick to: the JBN site reports an indiscretion that Apple is testing SIRI on older iPhone models. In the specific case, the model called into question would be 4, but Apple employees would have access to a special version of the personal assistant working on old devices. AppAdvice would also have confirmed the indiscretion, which therefore no longer appears isolated and gains greater vigor.
Despite there the doubts about this eventuality keep their strength: from a commercial point of view, the choice to bring SIRi on mobile phones previous to the iPhone 4S would be a typically "not Apple" decision which historically has always distinguished itself for the desire to want to make accessible some advanced features only on newer models. An example of the aforementioned video recording, available only on iPhone 3GS and not on 3G, despite the fact that many users had demonstrated the potential functioning of videorecording on the second iPhone through jailbreak.
If we consider SIRI from a more strategic point of view, installing the personal assistant on other devices could be a long-term winning move. SIRI could be a very useful tool for Apple to be able to challenge (and break free from) Google, now much more rival than partner.
To return many responses, in fact, SIRI uses services competing with those of the big G, such as Yelp and Wolfram Alpha, thus stealing space and searches in Mountain View, thus representing an alternative to Google, as recently admitted by Eric Schimdt himself, who has called SIRI "a potential threat" to the heart of Google's business, namely online search. Considering this aspect of Apple's personal assistant, Apple's decision to want to bring a "threat" to Google on as many devices as possible would thus be more comprehensible, so as to exponentially speed up the competition.
In conclusion, the arrival of SIRi on other devices will depend on Apple's strategy in considering more or less fundamental the greater diffusion of its personal assistant on multiple devices, to then reap the benefits as soon as possible, perhaps trying to abandon the current one (and in a sense still indispensable) link with Google.