http://gadgets.boingboing.net/2009/02/12/gps-chips-are-now-sm.html

GPS units are getting disconcertingly small: Epson and Infineon’s XPOSYS chip is just 2.8 x 2.9mm and can fit comfortably within the sulfurous volume of a single match head, while still having enough power to stay in contact with orbiting satellites. Gnash your teeth in holy dread, privacy activists: we’re fast zooming into a day and age where GPS nano-chips will be sprayable in a fine mist all over your body as you pass through airports customs. If we’re not there already, we’re rapidly enterting the age of ubiquitous personal trackability, with our only solace being informational mass entropy and the inherent incompetence of bureaucracy.

Reminds me of the Island of Dr. Moreau....Hyena Man finds a chip in the body of a dead creature and realizes this is what causes the pain.He refuses his injections saying “pain no more" as he tears out his chip.
http://www.youtube.com/watch?v=HbsIlsOlFtA&feature=relmfu  This youtube clip at 7 min 10 second