Do you need to use AGPS? It only takes 12 minutes to download the ephemeris and almanac via the GPS satellite itself. So even without Internet connectivity, you'll eventually know where you are.
I don't know if this is because the iPhone's GPS functionality is crippled, or if it's a software limitation. I'd imagine that if you wanted to overcome this limitation, you'd need to jailbreak your phone and use 3rd party mapping software at a minimum.
*Note: once it has located you, it will generally track you correctly while you're moving, even if you leave the area where you had internet connectivity.
The almanac is valid for 180 days, so you only need to wait 12 minutes once. From then on, you only need the ephemeris from 4 visible satellites, which takes less than a minute to download.
It confuses me that the iPhone wouldn't be able to do this, because I can buy a $10 microchip that's the size of a dime that can do it. Give it electricity, wait 15 minutes, the location comes out the other side. I would be shocked if the iPhone were incapable of doing this.
How do you know when the 15 minutes starts, though? Dedicated GPSs tell you things like how many satellites they have in view and how accurate their fix is, but dumbed-down devices like to pretend location is magic. I'd hope they'd at least provide the gritty details through CoreLocation so a user can buy an app if she wants to know which bench outside the train station to sit at sipping coffee while the phone orients itself.
The best you can do with CoreLocation is set desiredAccuracy to kCLLocationAccuracyBest and wait for it to fall below 100 feet with no way to find out if it ever will.
With the iPhone I get a decent location in seconds and a more accurate one in ten. Indoors.