via Livescience, the US Navy has produced and tested a devastating new weapon: the rail gun. Such weapons use electromagnetic energy instead of gunpowder as a propellant, allowing a muzzle velocity of seven to eight times the spped of sound and a range of 230 miles versus a conventional naval big gun range of 23 miles. An additional advantage is that the weapon uses kinetic energy rather than explosives to provide its destructive impact, making the deployed warships much safer for the crew. Theoretically, the weapon will provide a speedy precision strike weapon from extreme ranges without the possibility of bringing defensive missile weaponry to bear, such as in the case of a cruise missile.
"I never ever want to see a Sailor or Marine in a fair fight. I always want them to have the advantage," said Chief of Naval Operations, Admiral Gary Roughead. "We should never lose sight of always looking for the next big thing, always looking to make our capability better, more effective than what anyone else can put on the battlefield."
The Navy plans to deploy the weapon on warships during the next decade, hopefully by around 2018. If I recall correctly, one of the warships it is planned to be installed on is the next generation "stealth" DDG destroyer design. (After checking, yes it is).
More on the weapon here can be found at Military.com, condensed below.
The current test version of the weapon is a 32 megajoule weapon, the most powerful ever built to date, with a 64 megajoule weapon being planned for deployment. One of the weapon's teething issues is the tremendous amounts of electricity required for firing, 3 million amps for the test weapon and 6 million for the one planned. The planned electrical propulsion system on the DDG would have a capacity of 72 megawatts, and the planned 64 megawatts weapon would require 16 megawatts to fire, requiring the vessle to slow down in order to fire. Another issue is the need for high end material breakthroughs to prevent the gun's barrel and conductive rails from being shredded after repeated firings by the high velocities generated .
Cool stuff if we can get it out of development and into the field.