I've got a WiFi only iPad2, so the non 3G, non-GPS version of the device. And yet, using its maps app, it's capable of pinpointing my current location accurately up to a few meters! I'm absolutely amazed by this and have tried this at several locations, everytime with the same incredibly accurate result.

How does it do that? It's not like it can triangulate my position. I'm guessing the external IP address is used, but I've never known this to be very accurate. Usually it can only pinpoint the town you're in and most of the time not even that. So how does Apple do it?