As just three of what will most likely turn out to be a number of quiet changes to the iPhone 3G S hardware from its iPhone 3G predecessor, Apple has disclosed details of changes to the iPhone 3G’s headphone port, headset, and radiation emissions, which offer mixed news for users of the upcoming 3G S model. Since 2007, Apple has included the iPhone Stereo Headset with all iPhone and iPhone 3G devices sold worldwide, a pair of earbuds with an…