Skyhook. They used to be the world's largest database of wifi MAC->GPS mapping. Apple us building their own (as is Google and probably many others), but they ar

Skyhook. They used to be the world's largest database of wifi MAC->GPS mapping. Apple us building their own (as is Google and probably many others), but they are probably still handing some queries (and data) over to Skyhook when their own database is found lacking.