Parat Solutions offers the Parasync dock that is able to dock as many as 20 iPhone and iPod devices. It allows you to charge these iPhones/iPods and sync them from a single iTunes library.
The Parasync needs just a single USb connection. When connected, all 20 devices will appear in iTunes. The dock works with iPod classic, iPod touch, iPod nano 4G and iPhone and you have to specify model when ording.