Assisted GPS is true GPS plus faster initial position finding (that's the "assisted" part).<p>Anyone who's owned a hand-held GPS can tell you it takes a few minutes to find your initial location, especially if you've moved location since the last time you turned it on.<p>An AGPS system uses hints from cell towers to get a rough idea of where you are. This significantly lowers the time required to get a lock.<p><a href="http://en.wikipedia.org/wiki/Assisted_GPS" rel="nofollow">http://en.wikipedia.org/wiki/Assisted_GPS</a><p>So, yes, it will function without a 3G signal. The problem, however, is that when you're out of 3G range, you won't be able to download Google Maps data. So, if you need maps when you're out in the middle of nowhere, you'll probably want to buy the TomTom app, or one of the other "real" GPS apps.