It looks like Lockheed-Martin Missiles and Fire Control^* and the Missile Defense Agency are looking at testing an upgrade to the PAC-3 Patriot SAM in 2009. (paid subscription required)

It looks like the sensor for the hit-to-kill weapon will be much the same as its predecessor, but that range will be doubled and effective altitude increased by a larger diameter motor with a two pulse motor, giving generally improved kinematics.

To do this, they will put the missile in a PAC-2 cannister, the PAC-3 fits 4 missiles in the space of a PAC-2 now, and use folding fins for greater volumetric efficiency, and LM is hopingto be competitive in naval applications too.

^*Full Disclosure, in 1999-2000 and 1996-1998, I worked as a mechanical engineer for what is now Lockheed Martin Missiles and Fire Control, and I have some claim to actually being a rocket scientist.^†
†Yes, I have worked everywhere. Maybe I can’t hold down a job, but more likely this has been my role as “technical hit man”, where you are parachuted in to take care of a specific need.