GPS Tracking on the Uptick

I have noticed that the police are increasingly using GPS tracking devices to obtain evidence of drug activity.  The typical pattern is for the police to draft an affidavit describing the suspected drug activity "based on my training and experience" and seek permission to place a secret GPS transmitter on the vehicle-even including court permission to hardwire the device to the vehicle's power source.  In the past year it seems that GPS has become almostthe norm in my drug cases.  The technology is described here and here.