If you did indeed move your router across country you can fix your wifi location via this page: http://www.skyhookwireless.com/howitworks/submit_ap.php

(You can also game the system from this page if you prefer to play the griefer.)

But another point of interest is that it does not have to be YOUR wifi that moves, or even one you are connected to. Nor does it have to be connectible (by you).

Every packet from the wifi router carries its mac address, and the mac address is used to look it up in the Skyhook database.

Your iphone can see a lot more wifi routers than it will show you. (Download WifiTrak from the app store if you don't believe this).

The phone will get the mac address of every router it can see and it only takes one rogue router to slow down and make imprecise any position hints Skyhook supplies.

I live in a area that has a lot of Military Officers who live off base and have wifi. They never reset it when they move. They move fairly frequently. There always seems to be a Rogue Router in my neighborhood throwing off my location in one direction or the other, often by dozens of miles, which always made my GPS pindrop sloooow.

I went to the above page and registered MY router, and that seems to help.

Most info I have seen on this subject (including some on the infinion site, the suppliers of the AGPS chipset) suggests that the wifi and tower locations are fed to the AGPS chip as the starting location, making satellite acquisition faster. (The chipset knows which birds are overhead and the frequency to listen on given this hint).

The only time you get a blue-dot is when there is a satellite fix, not a tower or wifi fix.

And skyhook does not work at all if you have no network connection, (No wifi, no 3G no edge). This means your AGPS chip is on its own, and it can take it quite a while to work out its true position without these hints, but it will eventually.