The Army some time ago adapted the Navy's Phalanx anti-missile system, which rapidly shoots grenade sized explosives at incoming ordinance for point defense roles. The Army christened the system the Centurion, and has now developed a mobile version that rides on the back of a big truck. In Iraq, the main application has been to guard against mortar attacks.
Meanwhile, the Army is also developing a second generation guided artillery shell. The 155mm Excalibur B shell will cost $50,000 per shell, down from $85,000 for the original version (which was about the cost of a helicopter based Hellfire missile), and will have similar accuracy as well as an inertia guidance system to back up its primary GPS guidance system. The linked post reiterates the benefits of guided artillery shells over $300 unguided ones, a discussion presented at this blog several times previously. A Navy effort to copy the technology was cancelled.