While UMTS only uses one antenna, LTE have the ability to use two or more, just like wifi-n. Basically it allows them to not only divide a signal in time, but also in space, meaning there is more capacity available (yep, my mind is blown by the concept).

Now i am unsure if user-space programs will ever get access to the needed data to do anything like what is asked in this thread, but if they do a LTE phone should in theory be able to pick up the general direction of the nearby cell towers (in much the same way that the telco can help police and rescue by triangulating a phone in their network).

A different solution would be to wire up two phones so that they can share signal data, to much the same effect (i think someone in the openmoko community did such a thing as a lab experiment to map cell towers).