RadTech (http://www.radtech.com) has released the ProCable for the
iPhone and iPod. IT’s a 30-oin to USB and 3.5mm line-out audio cable.

The US$19.95 ProCable is designed to let you tap the high-fidelity
line-out audio from an iPod or iPhone and feed it directly into a
home or auto sound system. This cable also allows you to charge and
power said iPod or iPhone via a standard USB port. You can combine it
with RadTech’s ACpower USB charger for home set-ups, or with our
AutoPower in-vehicle charger when using the cable in a vehicle.