Newslink: Could Moon Miners Use Railguns to Launch Ore into Space?
The United States Navy fired a projectile at Mach 6 during a recent test with an electromagnetic railgun, suggesting that early ideas about using such tech to launch payloads from the lunar surface might not be so sci-fi after all.
http://www.space.com/36442-could-moon-miners-use-railguns-to-launch-ore-into-space.html
Read Moon is a Harsh Mistress, possibly the first time a 'mass launcher' was used in a SF story.