From Slashdot, looks like the US Navy has been busy, they plan to implement rail gun technology by 2011.
DD(X) is in development by the Navy, Northrop Grumman Ship Systems, General Dynamics Bath Iron Works, Raytheon, Lockheed Martin and other firms. When the new ship arrives in service it will be armed with very advanced, but conventional weaponry, including two United Defense 155mm Advanced Gun System cannons and an 80-cell vertical launch system for various guided missiles. But these systems are stepping stones to greater capabilities, according to Michael Collins, Navy IPS/electric drive program manager. This technology opens the door to advanced weapons, he said.
A report on Rail Gun technology can be read here. (PDF)