The iPhone 3G is the second generation iPhone that utilizes the latest in 3G cell phone network technology.  It was released in an eight GB model in June of 2008 and a 16 GB model in July 2008.  In June of 2009, the iPhone 3G was discontinued to make way for the iPhone 3Gs released the same month.  The iPhone 3G basically took what made the iPhone solid at launch and added assisted GPS and a few other usability features that made it possible to take advantage of 3G network speeds.

The iPhone 3Gs was released June 8, 2009 roughly a week before the iPhone OS 3.0 update was distributed for the model coming before it.  The biggest change in the 3Gs model came with the addition of built-in video recording function which was missing from the previous models along with a unique cut and paste feature.  The iPhone 3Gs focuses on bringing out the very best in the phone's interaction with the 3G network both over the air and simply using the phone's applications.

If you waited until now to make the jump to AT&T or upgrade your phone on their network, now is the time to get the iPhone.  The 3Gs model has all the features those who bought iPhones in the beginning wanted in the phone from the start.  Over time, Apple has made significant improvements to both the OS and applications on the phone that allows for the fastest response time no matter what you are doing with the iPhone.  If you are a current iPhone user and want to upgrade, you may not be eligible.  However, you may be able to negotiate with AT&T depending on the length of your contract, the length of time you have been with them and even sweet talking your way into a new iPhone.