It shouldn't be app-specific. It should be core functionality. Perhaps a gesture, like, if you put 2 fingers on the screen (one at the top, one at the bottom) a

It shouldn't be app-specific. It should be core functionality. Perhaps a gesture, like, if you put 2 fingers on the screen (one at the top, one at the bottom) and rotate them to correctly orient the content, then the Phone should take that as an order to change the orientation from portrait to landscape, or vice-versa... Possibly also add a "lock orientation" icon just to the right of the clock at the top centre of the display so you can lay down, gesture to change orientation, and then lock it.