It seems like they're using the iPhone for pretty much all intelligence, which makes sense. Custom embedded systems are non-trivial to design, manufacture, and

It seems like they're using the iPhone for pretty much all intelligence, which makes sense. Custom embedded systems are non-trivial to design, manufacture, and bootstrap software for (I've been involved in some capacity with several). You'd save significant effort and trivially enable many more features by relying on something as powerful and mature as an iPhone.