Google Latitude : Java Glossary

Google latitude used to let you keep track of where you friends are if they have cellphones and they want you to know where they are. It did not require everyone have a GPS (Global Positioning System) phone. It works with WiFi (Wireless Fidelity) using the location of the WiFi server to track phone location. When WiFi is not avaliable, it uses the location of the nearest cellphone tower, accurate to about 200 metres (218.72 yards). (It does not triangulate signal strength to multiple towers for greater accuracy.). If you are running the Google app and your phone is equipped with GPS, it uses GPS to locate the phone. Then it is accurate to about 2 metres (6.56 ft). I don’t yet know if that GPS accurate position is broadcast to other users, or is just available to you.

The phone runs a Google latitude application only when you want to discover the locations of others. At other times you can run some other app or turn the phone power to standby so that it can receive incoming calls and make its presence known to the cellphone tower network.