Okay, so Microsoft didn't actually say that outright. Actions speak louder than words though, and Microsoft's actions with Windows Phone 7 speak to high hopes for the future ubiquity of OLED-based displays. PocketNow reports that Windows Phone 7 engineers chose black and white backgrounds for a very specific reason.
Black backgrounds draw less power on an AMOLED screen, and white backgrounds work better for emails and improve text readability. Microsoft knows that OLED/AMOLED technology will be the future of phone displays. It has already started to gain quite a bit of popularity, and that will only continue over the next few years.
It's quite possible that Microsoft decided to get bullish on AMOLEDs because they believe that the upcoming iPhone will pack AMOLED screens. Whatever the truth is, we'll have a better idea of it once the first Windows Phone 7 series devices launch.