The U.S. Navy unveiled a new electro-magnetic rail gun today in Virginia. Although not expected to be fully operational until 2020 it is no less expected to eventually replace the standard 5 in. guns on Navy ships. Using electricity rather than gunpowder it will be able to launch projectiles at Mach 5 when fully developed.
http://www.foxnews.com/story/0,2933,327205,00.html
http://www.foxnews.com/story/0,2933,327205,00.html