MORE ON RETURNING TO THE MOON: This Yahoo! news article makes a good case for a sample return mission...from the Moon.

Yes, it's been done before, but only three times (other than Apollo, which is a different matter altogether). The idea, which sprang from a year-long National Research Council report on possible planetary missions in the 2003-2013 period, is to send a sophisticated sample return mission to Aitken Basin on the lunar farside. The mission would drive the development and (near-home) testing of a new generation of planetary geology probes and sample return systems, not to mention the landers required to get them to the surface, and the orbiting systems needed to communicate with them. Then the agency's sights would (theoretically) turn to the more ambitious sample return missions from Mars and...Venus? Yes.