Currently QtMobility documentation of QDocumentGallery::Image property orientation does not explain what those values mean. Returned orientation values seems to be some integers.

I suppose that value of orientation is directly Exif Orientation Tag so those values can be understand with:
http://sylvana.net/jpegcrop/exif_orientation.html
and
http://www.impulseadventure.com/photo/exif-orientation.html

As orientation is quite commonly needed information for applications that are showing images/photos it would be nice for developers that this information would be specified more thoroughly in documentation.