Universal Display is working on a ceiling OLED lamp, together with Armstrong World Industries. This is partly funded by the US Department of Energy, in a 2-year 2M$ grant (started July 2008). UDC have now released this video showing the OLED panel, which is 24-inch wide:

Kyulux - Hyperfluoresence OLED emittersKyulux - Hyperfluoresence OLED emitters