Can a GPS navigation device be tracked

Does anyone know if there's a way to track the location of a GPS device knowing its ID? Are there any websites where this information is available?

No, GPS location determination is a problem of precise time measurement (from the beginning of a special week), and sattelite identification. To not go into any details ... it is a one way signal from satelites towards earth, and can not be tracked.

http://en.wikipedia.org/wiki/Global_Positioning_System
http://en.wikipedia.org/wiki/Radio_clock#GPS_clocks

Differentical GPS's are a different matter.

Tracking via GPS navigation (this is a requirement which for example trucking companies have which enables them to locate their vehicles) is a "simple" mechanism of sending out GPS information (NMEA) via an automated SMS messaging service to a centralized location. Very simply put of course, but that is the basic principle.

http://en.wikipedia.org/wiki/GPS_tracking
http://www.uktelematicsonline.co.uk/