The biggest problem with GPS is that it does not work inside a building.

With dense enough Wifi AP mapping you are able to still at least point to the right house/street.

Tried it at work - stopped loads of spam, but had to disable it because out there are too many broken smtp servers (on short inspection mostly lotus notes) that think an return code of 4xx is a permanent error and bounce the mail.

And my boss is not happy when even ONE important mail from a client is not reaching him.