*Tossed out into the FWIW Bin*
I was told by a person who's unusually tech-savvy in this area that A-GPS in the 3G iPad didn't actually depend on you being connected via cellular or, for that matter, having a plan. All you need do is have cellular turned on and, I guess, you'd also need a SIM that worked for the region that you're in.
As I understood what he told me, it (cellular) only really does anything right at the start of a 'session' or period when location is being determined. It simply looks at the cell towers it can see and calculates a position based on that, then passes that info to the GPS chip which takes over from there. It helps the GPS get a better lockon or better position
bite, and get it quicker, but doesn't really contribute much after that.
With cellular off or not available, the GPS will try to do the same thing with wifi but, as already discussed above, this is less accurate and subject to not working if the database isn't completely up to date and which, realistically, is never going to be up to date.
Absent any initial data the GPS is still capable of getting and maintaining a fix, but you'll see larger circles and slower response times. And, of course, it won't do you much good unless you have some pre-loaded maps to display the info on.
+Which leads to a thought: Has anyone heard about any app which just displays the basic GPS data in more or less real time? Current lat/long, velocity, altitude, track? Sort of like a Garmin handheld might display?+
