it's trivial

Getting the screen right is indeed trivial -- it could all be done in a hypothetical Hipodjack, using merely a substantial amount of coding work. The real barriers to running an unmodified Empeg car-player binary on a Linux Ipod include the ucLinux-vs-Linux issue, power management, and the CPU performance -- the Ipod Linux guys say that even madplay doesn't run real time, which means they're getting about 1/6 the performance of a car-player out of it. Plus I'd be slightly surprised if our licence let you make copies for such a purpose.

Peter