Maybe this is well known around here already, but I just discovered it the other day:

http://freegeographytools.com/2011/how-the-fcc-plans-to-destroy-gps-a-simple-explanation

Basically it goes like this:

Some corporation wants to provide cheap mobile internet. Buying a license for the normal spectrum would be expensive so they bought a license to transmit from satellites on some frequency. (I am not sure how this works with phones and how this frequency is different from the one they could acquired on normal ways.) Now, having such license for satellite transmission allows you to build terrestrial support transmitters, for example to cover areas of bad coverage. So now they can simply build base stations as "supplementary" stations and provide cheap internet.

What's the problem? The frequency band is right next to the GPS L1 spectrum, the spectrum our dear handheld GPS systems use. And since they broadcast "slightly" stronger than what we receive from the satellites, they ultimately jam the GPS frequencies if you get too close to such station, which in a city might be inevitable.

If only this was about a frequency close to L2, the frequency the military uses for their encrypted GPS signal... :-)