The X Prize this time is for the first privately funded organization (TrekBBS?) to land a rover on the moon ($20 million, $5 second prize, and $5 million bonus to the winner for completing certain missions tasks).
The official rules and competition guidelines are here:
http://www.googlelunarxprize.org/lunar/competition/guidelines
The official rules and competition guidelines are here:
http://www.googlelunarxprize.org/lunar/competition/guidelines