Windows Phone 7 Series: 800×480

Microsoft’s Charlie Kindel: for now, Windows Phone 7 Series (WP7S) will only sport a pixel format of 800×480 (landscape). And for some odd reason we can expect a lower-end 480×320 to join some time in the future. Keep it simple guys: stick to just 800×480 and forget about 480×320. Source: Engadget