As shown on the Features page of the soon-to-be-released iPhone 5S, the device contains a brand new M7 co-processor alongside the new A7 chip. The M7 coprocessor is a motion controller and it is there to increase the ability of the iPhone 5S to constantly measure motion data from the array of sensors inside the phone. As Apple states, these include an accelerometer, gyroscope and compass. While these tasks would normally by performed by the A7 processor, the M7 takes over and is much lower power, meaning that the device can constantly measure the outputs of the motion sensing without draining power.
While the M7 chip can primarily be used for sensing of human movement i.e. exercise, there are other potential uses for it. A 9to5Mac report suggests that Apple is also working on a way to use the M7 chip to measure the location of a parked car, predominantly by sensing where it is parked and the dropping a pin. While not a terribly complicated undertaking, it is software that is currently not incorporated into the Apple Maps app.
With the iPhone 5S launching next Friday, it will be interesting to see what other hardware based features Apple has incorporated, that can be used in future app technologies.