Many Windows users have expressed concern that Windows 8, much like Windows Phone 7, could be perpetually locked in landscape mode. Recent news from Microsoft has explained that although landscape mode is the most popular orientation, Windows 8 will definitely be optimized for portrait mode as well.
According to a recent blog by David Washington from the Windows 8 user experience team, many users prefer to view some specific content while in portrait mode, such as websites, Twitter feeds, ebooks, etc. and that Windows 8 will make it simple for developers to include landscape and portrait modes within their apps.