From Earth Magazine:
Until recently, the consensus in the scientific community was that the moon was bone-dry. Scientists thought that the massive impact responsible for the moon’s creation would have driven away the hydrogen needed to form water. In the past four years, however, that view has melted away. The first suggestion of water was in 2008, when researchers identified the presence of water in volcanic lunar glass. In 2009, satellites orbiting high above the moon identified water on its surface.
A version of this story appears in the February 2013 issue of Earth Magazine. For a pdf, please email email@example.com