Tom Tom Mobile 5

A demo of the Tom Tom Mobile 5 software on a Symbian phone

Is it true that all GPS receivers also transmit their location to GPS master control station?

Today’s reader question comes from Deepak.
Here’s what he’d like to know:

I have heard that all GPS receivers also have a high frequency transmitter and the receiver body itself acts an antenna and the ID and location of the receiver are continuously being tracked by GPS master control station though the satellites.

How do GPS satellites stay in perfect position with out drifting out of position in time?

gps
Another Reader question about GPS Satellite positioning, from PeterD:

Seems that no matter how perfectly positioned these GPS satellites are they would drift out of position and that would throw off the computations of our GPS units in cars etc.