I have had the exact same thought. I *love* linux and my car, but pricing it out I could just buy a pile of individual devices to cover everything a car pc could for less than the $1000
for a PC and touchscreen
- gps units
- deck with ipod control/USB
- phone does data plan (even TV) already
plus, without a serious speech to text interface, I'd be afraid of crashing the car as a distraction - I can't even control my ipod.
10 years ago, it might have made sense, but now....dunno.
I think the real challenge/interesting part might be creating clean housing/mounting for all the devices above.