The base station plugs into the audio jack; a storage case doubles as charging station.
Next to the audio jack, in the center of the phone, resides a connector used for data transfer and charging.
The 30-pin connector isn't quite as easy to slide in as it once was, and the audio jack on the top is a bit more awkward.
These features are achieved by a fourth ring in the audio jack that carries this extra information.
Your PC at work does have an audio jack, presumably.
First, as mentioned, it has an audio jack to connect other audio devices.
All the input methods except the audio jack are colored in a secondary color to raise its affordance.
The audio jacks are made of gold plating for performance.
The key difference (aside from size) is the audio jack and speakers on the Touch.
There is some consolation for rear passengers: In the test vehicle they had their own air vents and audio jacks.