The reason the Kindle and other electronic-ink displays use black and white is that without a light source, rich colors are hard to produce. Here is an example of HP Labs' "roll-to-roll" plastic display manufacture technology using color electronic ink. HP Labs uses three different layers of colors to produce as bright colors as possible.
Future applications include wrap-around displays for gaming and retail store signage.
Inside HP Labs in Palo Alto, plastic displays are being tested to replace glass displays, which are currently standard for most portable devices. Plastic will lead to very thin displays that are lighter and therefore cheaper to produce.
Shown is a sheet of plastic with resistors etched in a process called imprint lithography. The plastic is 50 microns thick, or half the thickness of a piece of paper. It weighs 40 times less than glass normally used for displays.
One example of an actual product using this technology: the flexible wrist display currently being made for U.S. troops. Using flexible solar cells for charging the display worn on the wrist, it uses e-ink to show each wearer relevant information.
A company called Phicot, which was spun off from HP Labs, is producing the wrist displays. The first prototypes will be available in 2011.