As you probably know, the GDR2 Windows Phone update was accompanied by the Amber update for Nokia Lumia users; this brought some new features and capabilities to Lumia phones. One of those features was the glance screen which right now only shows an always on clock and alerts you as to whether your phone is on the 'vibrate' setting...Source: http://www.phonearena.com/news/Bittersweet-shimmer-brings-color-options-to-Nokia-Lumias-glance-screen_id48014
