Google Latitude : Java Glossary

Google latitude lets you keep track of where you friends are if they have cell phones, and they want you to know where they are. It does not require everyone have a GPS (Global Positioning System) phone. It works with Wi-Fi (Wireless Fidelity) using the location of the Wi-Fi server to track phone location. When Wi-Fi is not avaliable, it uses the location of the nearest cell phone tower, accurate to about 0.20 km (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 cell phone tower network.