Siri, the artificial intelligence personal assistant from Apple, has been the main draw for those wanting to update to the iPhone 4S.

Industrious hackers and crackers have already figured out a way to make Siri run on older iPhones and the fourth-generation iPod Touch, but now a report from JailbreakNation shares that an unnamed “source close to Apple” has found that the company is testing Siri on devices other than the iPhone 4S.

“The device specifically mentioned to us was the iPhone 4,” the blog wrote, adding that the source reports that the assistant could be hitting older phones in the form of a software update “soon.”

I’d take this rumor with a lot of salt, but the software clearly works on the iPhone 4, at least according to videos posted on 9 to 5 Mac late last month.

Speculation was that Siri would not come to the iPhone 4 because the feature probably ran best with the 4S’s upgraded processor. CNET’s Josh Lowensohn also points out that Apple has never released a major feature like this in a software upgrade before, though he does mention that much of Siri’s processing doesn’t rely on the phone. In fact, the service was available as a stand-alone app before the iPhone 4S was announced.

Siri, which is still being advertised as a beta service, had some issues last week when Apple reportedly had “server problems.” Even with the requisite connection to the Internet, the assistant wasn’t answering queries except with the message that she was having problems connecting to the network.

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Siri works even when phones are locked

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