Lightsquared is completely in the wrong . . .
DOD was one of the earliest objectors to LightSquared. The full details of their tests are, naturally, classified.
LightSquared wants to use, for terrestrial purposes, a band that is internationally set aside for satellite use only (at substantially lower power levels than LightSquared wants to use on the ground).
The precision GPS users (military, aerial navigation, precision agriculture, civil engineering to name a few) are the worst-impacted, and they're using multi-thousand-dollar receivers, usually many of them.
Glonass and Galileo are affected too, as they use the same part of the spectrum that the American NavStar GPS uses. And if LightSquared manages to pull this off, count on them, or competitors, to want to go world-wide with this, so don't pretend that an ocean makes you safe from this.
LightSquared is most analogous to light pollution. You may not notice that you can't see as many stars when that street light goes up nearby, but when they build a brightly-lit shopping mall there, you'll start to see. And the astronomers would have noticed the street light. Precision GPS is the astronomers in this case. Give LightSquared what they want and you'll start to see the problems yourself. Tests to date haven't used the full spectrum LightSquared wants to use, haven't used their signal at full power, and have only used a single tower, not the forest they want to build. And they're still showing massive disruption to the adjoining frequencies.