From Forum Nokia Wiki

GPS was originally developed by the US military for defence purposes and is based on a system of 24 satellites which orbit the earth. A GPS receiver can triangulate its position using Time Of Arrival (TOA) methods as long as at least three satellites are visible. Typically accuracy is around 2 to 10m although higher resolutions can be achieved. The cost of GPS hardware continues to fall and GPS positioning remains a free service to consumers. Integrating GPS hardware technology into cellular phones is one of the main positioning solutions being explored by handset manufacturers.