Microsoft built a pair of keyboard covers to sell alongside the Surface tablet--the Type cover with physical, moving keys, and the Touch cover, a thinner, softer screen protector that uses touch technology to emulate the keys of a keyboard. At 3.25mm, the Touch cover is thin, but it's just been one-upped by a prototype touch surface developed by semiconductor company CSR. At IFA in Berlin, CSR just showed off a touch surface about 0.5mm thick, or about the width of a human hair.
CSR envisions the touch surface being used as a portable keyboard and tablet cover, just like Microsoft's Touch cover. The difference is, it's flexible and inkjet printed, meaning it could be used in all sorts of sizes and situations. The capacitive touch surface will work with a stylus, so artists could conceivably buy a desk-size, paper-thin drawing surface to replace a dedicated drawing tablet.
The touch surface is wireless and runs off of a Bluetooth Smart connection. In the hands-on linked above, Wired writes that the flexible membrane "feels and looks like a piece of paper made from glossy plastic" and is surprisingly easy to type on and works just as well as a touchpad. The surface is so thin, it obviously can't house the electronics needed to make it function; a chip attached to one side of the surface houses the Bluetooth communication, battery, and everything else needed to convert finger presses into wireless signals.
CSR put together a short-but-sweet video showing off the prototype--check it out below. If a final product is cheap enough to print in large sheets, touch surfaces could be much easier to implement in tons of situations.