Apple has just been awarded a patent (U.S. Patent No. 8,638,549 for those interested) for a very peculiar display. With an abstract that begins with the overwhelmingly generalized statement that "electronic devices may have housings," this patent goes on to describe a dual-screen laptop whose second screen is mounted on the outside of its casing.
This theoretical screen would be comprised of multiple laminated layers. Among many possible uses for these layers, the patent makes mention of a touchscreen interface and solar cells. This has given rise to the theory that Apple's new laptops could be solar powered, with touchscreen controls mounted outside to monitor charge status. While this could be where Apple is headed, the patent's illustrations depict a small rear-mounted screen — one impossibly small for efficiently charging or continually powering any laptop.
We're more of the mind that this small second screen is for checking on alerts and receiving messages without having to fully unpack your computer. The inclusion of a built-in solar cell is likely to allow your laptop to remain (mostly) charged and dormant while you use the secondary screen. There's even mention of an antenna, similar to that in modern iPhones, being formed around the outer edge of this new display, meaning that, if the tech in this patent ever sees the light of day, future laptops could have second screens with their very own means of connecting with the world, even when the laptop is off or out of battery.