First filed for in 2009, Apple's U.S. Patent No. 8,386,677 for "Communicating location information between a portable device and an accessory" allows for any portable media device, including iPhones and iPads, to exchange GPS data with a separate accessory through wired or wireless protocols.
The patent covers a location-enabled device sharing data with non-location-enabled one, the reverse and a sitaution where both have location information and the perceived "most accurate" location is used for the task at hand. Apple Insider suggests the patent is intriguing in the context of the recently reported iWatch.
Location data is exchanged between a portable media device and an accessory. If the portable media player is equipped with location determining capability, the portable media device can communicate its location data to the accessory, and the accessory can use this location data to perform various tasks. If the accessory is equipped with location assistance capability, the accessory can communicate location data to the portable media device, and the portable media device can use this location data to perform various tasks.