These new displays don't need backlighting and will be visible under direct sunlight. CleanTechnica has some more information:
Samsung unveiled the world’s first carbon nanotube color active matrix electrophoretic display (EPD) e-paper recently at a conference in Korea. The 14.3 inch e-paper display is the product of a partnership between Samsung and Unidym, the company that developed the carbon nanotubes used by the device.
The display has a variety of advantages over traditional flat panels. Since the EPD doesn’t require backlighting, it uses minimal energy and is visible under direct sunlight. Additionally, the image on the display is retained without the need to constantly refresh.