CSS-Based Image Orientation Comes To Firefox 26
The new CSS image-orientation property, supported in Firefox 26, is the answer once applied to a JPEG image. In use, it'll "take its EXIF orientation tag into account when performing layout and rendering." In other words, by adding just a single CSS property, smartphone and camera images will be displayed in their correct orientation.
Hopefully, the inclusion will become commonplace across all browsers in due time. It sure feels like one of those things that should've been sorted long, long ago.