The front is literally apane of polished glass and it exhibits the same properties -- oils and fingerprints are basically invisible when the screen's on, but they show up when off (and in the black zones above and below the screen).
Unfortunately for the textbooks, the latest estimate, made by Yvonne Stokes of the University of Adelaide, and which will be reported in the Proceedings of the Royal Society next month, is that it would take over 10m years for a window pane to flow perceptibly.
The new Twitter is out, and my colleague Quentin Hardy has a fine post about how the double-pane format allows it to display more information and content.