They discovered a significant amount of water in the Moon's Cabeus crater

The LCROSS probe, designed to determine the presence of water at the Moon's Southern Pole, targeted the permanently shaded Cabeus crater to crash into and eject enough material for analysis. Approximately 25 gallons of water was reported to have been found as a result.

NASA used a space probe and its monitoring craft to purposefully crash in to the Moon's Cabeus crater to kick up particles for analysis. The crater is in an area permanently shaded at the Moon's Southern Pole. Though it took a month to do the spectral analysis, they did determine a significant amount of water from the crash of both the empty rocket hull and the LCROSS probe itself.

The LCROSS probe (Lunar Crater Observation & Sensing Satellite) slammed into the Moon as expected, though the resulting plume was hardly what was expected or advertised. Still, they were able to determine about 25 gallons of water was released, meaning there's a lot more on the Moon than previously believed. Water particles have always been found in molecular quantities in moon dust, but never in the quantity found recently.

The implications are huge - not only does it potentially mean that a base could use local water for supply, it can use it to manufacture rocket fuel as well.

On June 18th of 2009, NASA sent a probe in space called LCROSS (Lunar CRater Observation Sensing Satellite) to crash into the south region of the moon near the Cabeus crater. On the 9th of October of that same year, the space craft crashed into its target with dead aim precision. the LRO or Lunar Reconnaissance Orbiter, another probe sent at the same time as LCROSS took spectrometry data from the cloud of debris that was ejected from the surface of the moon seconds after LCROSS impacted the Earths natural satellite. Spectrometers look at gases and by looking at the rate of absorption of light, scientist can determine was molecules are in the substance being observed, since each molecule has its very own unique spectrum lines (the colors of the rainbow). for example if looking at mercury gas we would see blue green and orange lines of color where as in hydrogen gas we would see violet blue aqua and red. The data from the spectrometers show very clearly that the spectrum for water in present.