edparsons.com has a revealing post about unlocking the Nokia N95 A-GPS capability by following their firmware upgrade instructions . Contrary to the post's position that A-GPS systems are “independent of network operators and does not use the location of Cell towers” to acquire mobile location fixes, A-GPS server systems are in fact not independent of wireless carrier networks.
While it’s true A-GPS queries tunnel under networks over IP (which makes them Internet friendly), the server system nonetheless uses Cell-ID data to produce base station almanac data server-side, which is subsequently used to compute the aiding ephemeris sent to the device to help it find itself. How else would an A-GPS server know how to gather locale-specific ephemeris data needed by the requesting device!?
If another hacker can figure out a way to get wireless carrier-owned cell-ID databases coupled with an A-GPS server independent of the wireless carrier, well that would be something to write about, but be careful—you could get sued.