The Lunar Reconnaissance Orbiter has been spending the past months calibrating its instruments since its launch in June. Its camera works best at an altitude of 50 kilometers, but it takes fuel to maintain such an orbit, so the orbiter has been spending its time in a commissioning phase orbit while it calibrates its instruments. The commissioning phase is now over, and the LRO has executed a 3 minute burn to put itself into a polar orbit 50 kilometers above the Moon, where it will spend the next year taking images of the surface and studying the Moon.
The LRO has already given us pictures of the Apollo landing sites and other locations on the Moon during its commissioning phase, but it should give us even better pictures now that it is officially in business.