It means that lunar colonization is possible and (relatively) affordable.
Hauling materials up the gravity well from Earth to the Moon is expensive, in terms of money and fuel. The most important materials we would have to haul would be air (which is rather light, and can be compressed) and water (which is heavy, and cannot be compressed). With water already on the Moon, we can haul up seeds and tubing, and thereby grow foodstuffs; with foodstuffs, the lunar colonists can feed themselves; if we had to constantly haul water up, we'd exhaust our terrestrial patience and resources.
We'll have to haul up the initial makings for solar cells and ore mining, but with the nigh-unlimited sunlight, the colony should be able to generate plenty of power, and contribute resources for building satellites and spaceships, necessary for mining the Asteroid Belt.
The idea of building spaceships at the bottom of a gravity well is insane. Better to build such things in Lunar orbit.
Rah, rah, RAH!!!
Yep. The limitation on the proposed Mars mission that would make it one-way is in large part the fact that it has to escape from the Earth.
Plus the ships wouldn't have to have beer transported to them from the Earth. They'd only have to worry about food and other inessentials.
I believe that the presence of water would mean that the colonists would be able to generate their own oxygen and fuel (H2), due to the pretty much unlimited solar energy available for hydrolysis (sp?)... not to mention the billion-year-old bottled drinking water market revenue ;-)