Mitsubishi Electric announced that it has developed an LCD panel that displays images on both sides.

Mitsubishi Electric's LCD Panel will enable phone manufacturers to use a single panel, reducing the weight and production cost of mobile phones. The company is also expected to develop the two-sided displays for use in laptop computers.
One version of the new LCD Panle allows a single image to be viewed from both sides of the same panel. The image isn't adjusted depending on the viewing direction, so from one side text appears correctly and from the other side it appears reversed. A second version gets over this problem by rapidly changing the image on the display in syncronization with each back light 120 times per second so that the same image, correctly displayed, is projected in each direction 60 times per second.
More Details on IDG Singapore.