And since NASA's been studying the concept since 1972, I'd call it less science fiction than a Space Elevator, which requires mass production of materials which we cannot currently produce in sufficient quantity to make. . ."
You and I will be long dead before any of this happens.
I was part of a major study on using (possible) lunar ice deposits (at the South Pole) as a propellant source.
It would be melted, electrolyzed, and shipped to an in-space depot for use by Mars missions.
The problem is that emplacement of the infrastructure (nuclear reactors, vacuum-tolerant digging equipment, supplies, spares, shops, mechanics, doctors, infirmaries, et al) make the payoff a distant (if ever) eventuality.
The same problem faces any scheme that purports to use Lunar materials for space-based construction: there is no infrastructure in place, and the costs of emplacing it kill you. The way I put it, "If God were to put the stuff there for us--for free--it might begin to make economic sense."
Better to work on a space elevator, which has a nearer-term likilhood of becoming real.
See:
http://www.liftport.com/
http://www.spacedaily.com/news/future-00n.html
http://news.bbc.co.uk/2/hi/technology/2188107.stm
http://www.space.com/businesstechnology/technology/elevator_update_020819.html
http://www.wired.com/wired/archive/11.04/nanotech_pr.html
http://www.sciencenews.org/20021005/bob9.asp
http://www.elevator-world.com/magazine/archive01/0211-002.html
http://www.americanantigravity.com/highlift.html