Universal Display and Armstrong are showing their efficient white OLED lighting ceiling system. Each luminaire is built from four OLED panels, each 15cmX15cm (overall size is 15cmX60cm), mounted in outcoupling enhancement lenses. The demonstration lamp has four luminaries. Each panel offers 58 lumens per Watt (lm/W) which translates into a luminaire efficacy calculated to be 51 lm/W.
This lighting system has been developed with the help of the US Department of Energy (DOE) - which gave a $1.9 million grant in July 2008. Here's a short video that UDC released in July 2009 showing a prototype system: