Microsoft is running as fast as they can to keep up in the wireless phone and mobile market, which is quickly getting dominated by Apple and Google Android phones. Even though Microsoft was one of the first movers in the market originally, they have not been able to keep up. With the announcement of Windows 7 Phone, they are attempting to get back in the game, and get more into the consumer / entertainment market, it seems.
The OS is based on a widget sort of layout, looks very much like Windows 7 in font and display, and appears pretty easy to follow along with.
Check out the story here, and also a nice review on ARS Technica