I'm guessing the extra space on the display will be for navigation keys. This way, the navigation keys aren't using up valuable screen real estate. It would be nice to have navigation keys not shown as an overlay on the actual content.
I've always said even long time ago when the debate on hardware/capacitive keys vs on-screen software keys raged on that that's what they should do. Just have a dedicated portion of the screen for software keys that wouldn't overlap the actual content.
Software keys are SO much better than hardware keys.