According to a new screenshot of an unspecified development build of Windows 8.1, Microsoft has made a minor change and renamed 'Computer' to 'This PC', while also removing the Libraries feature in favor of top level folders that sit inside 'This PC'. These folders appear to be the same as My Documents, My Music, My Videos, (etc.) just with the 'My' prefix removed and a repositioning into an easier to access location.
Source
A Guy