Dave must have been working on the site today, because there is now an option for dwarves to rotate a photograph in 90° increments before approval.

However, how a couple of people can persistently submit pictures turned on their side or upside-down in the first place defeats me... but at least this feature will avoid the need to refer such aggravation to Snow White... but if the culprits happen to be reading this, please re-orientate your pictures yourself and don't rely on others!