The iPhone (3G, 3GS, and 4) and the 3G iPads have fully functional GPS hardware, and also use A-GPS to acquire a position fix.
If you've ever used a normal standalone GPS in one city and gotten on a plane and flown across the country and tried to use the GPS again, you'll know that it can take 5+ minutes to reacquire a fix that first time off the plane.
If you've ever used a normal standalone GPS in one city and gotten on a plane and flown across the country and tried to use the GPS again, you'll know that it can take 5+ minutes to reacquire a fix that first time off the plane.