The FAA, as requested by the Executive Office of the President's Space-Based Positioning, Navigation and Timing (PNT) Executive Committee's National Coordination Office (NCO) Director, (what a mouthful) has delivered a report on the expected impacts from interference due to LightSquared's terrestrial broadcasts.
These impacts are big, including the estimated loss of 800 lives - or rather, lives that would have been saved by moving to GPS technologies - something that is impacted by LightSquared interference.
Here's a list of the expected impacts (from their Executive Summary):