If this isn't cool I don't know what is. I've known about this for a while and if you've watched certain shows on Discovery or the History Channel or even the Military Channel then you've probably known about it too. There's also one in Tranformers 2 the movie but of course that's just a sci-fi envisioning of the real thing, which is actually coming to a battleship near you real soon. I found this article in TheWeek.com.
Link to Story
There's also some vids on YouTube:
To quote from the article linked above, " The Office of Naval Research (ONR) is now test-firing a working prototype of the weapon that's small enough to fit on a warship. Using electric pulses, not chemical explosives, the cannon can shoot a 40-pound metal slug from New York to Philadelphia at up to 5,600 miles per hour — more than seven times the speed of sound — with 32 times the force of a car traveling at 100 miles per hour.".
I've seen better tests than in this video and if you look around YouTube you'll find them. For something that's supposed to have been under-wraps it hasn't been that secret, but, now they're announcing it so it'll be world news. From what I've heard these weapons can do a lot more impressive things than what they're saying in the article. I've heard they're even considering using railgun magnetics with what's basically a giant "Hot-Wheels" track looking launchpad to shoot stuff into orbit.