A patent discovered by Patently Apple suggests that Apple may use a magnetic compass and supersonic tone technology to share data between your iPhone and other electronic devices. In this new peer-to-per communication system, a magnetic compass is used to monitor the magnetic signature of a compatible electronic device. Once these devices are close together, they could automatically recognize one another and share information seamlessly without user intervention.
In another scenario, a device with a speaker could output an encoded supersonic tone that changes the local magnetic field. This change in the magnetic field can be detected by the receiving device. The supersonic tone is not audible to human ears, but it may drive your dog bonkers. Once the tone is detected by the compass on the portable device, the two devices will open a connection and share contact information, images, media and other files. Similar to a MAC address for a Wi-Fi-enabled device, these signatures may be unique to each device. Once detected, the signatures could be stored and recognized for later use.