Philips' transparent OLED lighting
We're still looking at another 3 to 5 years of development here, but transparent OLED lighting panels are definitely on the way. This 12-centimeter prototype panel developed by Philips Research is transparent until flipping the switch for illumination. Unfortunately, the panels are currently limited in size due to complexities in the manufacturing process that necessitate a clean-room environment.
Source: engadget.comAdded: 19 March 2009