Seiko Epson Corporation developed an OLED display capable of producing what the company calls "the ultimate black."

Besides displaying the ultimate black the Epson OLED display has increased longevity.

Epson's light-emitting materials achieve a life of 50,000 hours, a level appropriate for practical application.
The Epson OLED display has a size of 8 inches and a resolution of 800x480px. The brightness is 200cd/m2 and the contrast is 100,000:1.

Epson will exhibit this new OLED display system at FPD International 2007, an international exhibition of display technologies to be held at Pacifico Yokohama starting October 24th.
Via this Seiko Epson press-release.

While some companies like Epson are still researching OLED displays, Sony already released an OLED TV with the Xel-1 OLED TV.