Microsoft expecting most Windows Phone 7 devices to use AMOLEDs
Pocketnow reports that Microsoft's engineers chose black backgrounds in Windows Phone 7 because it will be very useful with AMOLEDs (it'll save a lot of energy because OLEDs do not use any power on black pixels). There's also the option for a white background, used to enhance readability.
It's great to hear that Microsoft expects most devices to have AMOLED displays, although this is not really a surprise - back in January we ran a story that Microsoft will advice device makers to use AMOLEDs...