According to the patent, and images obtained by Patently Apple, the device would use a slap bracelet to wrap around your wrist. Power could come from the use of solar and kinetic energy. According to the patent application, "Active communication between an accessory and a portable electronic device can be accomplished wirelessly. For example, a wireless data connection such as the 5 GHz 802.11n protocol can provide sufficient data transmission bandwidth to transmit a high quality video stream." The application also explains how this device, being worn on the arm, could provide a traveler with a look at a map with a "flick of the wrist." Blinking lights on the edge of the display could alert users to an event.
According to Apple, the device can also be used as a light for night time bike riding while wrapped around an arm or leg. And a gyroscope or accelerometer helps orient the screen correctly.
It seems that everyone has been waiting for Apple's next innovation. This could be it.
source: USPTO via PatentlyApple