Video: Anti-Everything Gun

It's called the Phalanx CIWS (Close-in Weapons System)Look for the product data sheet link on that page for geek info. All info is Public Released.

There's also a variant called the SeaRAM, it's a standard RAM (Rolling Airframe Missile) launcher hooked up to that big tracking dome thing in the video (white "head" looking thing) used to take down incoming aircraft, boats, etc. It also works against missiles.