The iPhone 3GS is the third generation of iPhone designed and marketed by Apple Inc. It was introduced on June 8, 2009 at the WWDC 2009 which took place at the Moscone Center, San Francisco.
Its features primarily consist of faster performance, a camera with higher resolution and video capability, voice control, and support for 7.2 Mbit/s HSDPA downloading (but remains limited to 384 kbps uploading as Apple had not implemented the HSUPA protocol). It was released in the U.S., Canada and six European countries on June 19, 2009, in Australia and Japan on June 26, and internationally in July and August 2009.
The iPhone 3GS runs Apple’s iOS operating system, as is used on the iPad and the iPod touch. It is primarily controlled by a user’s fingertips on a multi-touch display.
The iPhone 3GS is preceded by the iPhone 3G and succeeded by the iPhone 4.
Design
The iPhone 3GS retains the same design its predecessor used which featured a glossy plastic back with tapered edges which gives users a better grip of the phone. It also features metal buttons just like its predecessor’s. The iPhone 3GS and its predecessor are almost identical though the 3GS is differentiated only by the latter’s reflective silver text on the reverse side which now matches the silver Apple logo, replacing the 3G’s grey text. Unlike its predecessor, the iPhone 3GS was available in white and black for both models (16 GB and 32 GB) although the current 8 GB model is only available in black.
Bootrom
iPhone 3GS models with new bootroms started appearing in mid-September 2009 which had blocked the “24k” exploit used in previous bootroms which were used mainly for ‘jailbreak’ purposes. This made devices with the new bootrom harder to ‘jailbreak’ although not impossible. This marked the first time Apple slightly modified their devices midway through its supposed cycle (usually a one year cycle).
Source: http://en.wikipedia.org/wiki/IPhone_3GS