One of the most anticipated features to be included with the iPhone 3G is the inclusion of a robust GPS system. The Apple engineers seem to have come across some nice solutions to problems that have plagued other GPS enabled phones.

A nice aspect of the iPhone 3G's engineering is that it stuffs a lot of wireless tech, like 3G, Wi-Fi and GPS into just two antennas. However, that doesn't necessarily mean that it's always going to get a solid GPS satellite signal, like when it's indoors or between skyscrapers. To overcome this obstacle, it uses assisted GPS, also known as aGPS or A-GPS. The definition of assisted GPS can vary.

In the case of the iPhone 3G, it means location is determined with a combo of GPS, Wi-Fi and cell towers, depending on what's available. There are multiple benefits to A-GPS, such as the fact that it’s much faster. With standard GPS technology, to get a lock, you need several strong signals for a fairly decent amount of time. With A-GPS, the assistance server tells your iPhone where the closest satellite is and does the serious number crunching needed to cut down the number of frequencies the phone needs to scan making the whole process extremely faster. All of this helps to extend battery life, in theory.

One of the best things about the iPhone 3G's setup is that the location indicator shows how accurate the assistance server's calculations are, like when it derives your location in unfavorable conditions. Unlike some phones' aGPS, Apple states that the iPhone 3G’s A-GPS will still work even without a cell signal.

One of the unknowns about the iPhone’s GPS functionality is how much it will impact the battery life. The iPhone activates it "quickly and automatically" when needed. But not enough tests have been run to determine how long the battery lasts when the GPS is used for extensive periods.