Slightly anecdotal, since I got it from the source (I would hope; been burned on that before with a "Why does it taste so salty?" story).
An acquaintance in the dance community has an iPhone. With the phone turned off (not powered down, of course) inside her purse, she mentioned to someone that she was thinking of going to a particular locale after this. Soon as she got into the car and turned her phone on to check it, Siri was already giving her directions to that locale. That's her story and she's sticking with it.
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