I agree it woould be a nice addition but for $250 it's a little out of my reach for a car.
I know that this can only be bought as part of a complete keyboard system, but the MediaPad seems to offer track info etc in it's LCD for an mp3 player, great for remote control of your car pc.
Audi S8 supercar
Modded Xbox 400GB HD
Rear 7" screen & navplus
Toyota Hiace Van
Shuttle PIII 866 256Mb 10GB OPUS powered
MediaCar & Mappoint 2004
Custom fit 7" TFT VGA TSK