It’s the full 18 wheels too. The trailer is the iPod dock that features the dock, speakers, and controls.
The cab portion is the transforming Optimus Prime. Apparently the trailer portion even does some transforming of its own, which allows it to conceal the dock and speakers.
You can order them from Mugen Toys for $150. They should be available soon considering they just started shipping in Japan.
Optimus prime 18-wheeler ipod dock [via technabob]