The iPhone 5 is still a Retina display, with two pixels for every point. That's what the @2x suffix for graphics is used to indicate, so the same suffix will be used here.
As others have suggested, there is one new piece of required artwork in the [email protected] startup image, without which it appears your application will not be recognized as supporting the iPhone 5's display.
Beyond that, the only reason you would need special graphics for the iPhone 5 is if you had keyed something off of the overall dimensions of the screen. In that case, you'll need to detect the main screen's frame and substitute appropriate graphics at runtime using your own naming convention.