Well, someone's been paying attention to the car PC modders out there, because they're showing off a production unit at CeBIT. I think that something like a car PC can really only be done well by DIY'ers, though, because you're either going to get not enough/way more than you need, or you're going to get grossly over-charged if a company pre-makes/-installs it for you... You can see a couple more shots of it here.

"The as-yet-unnamed computer, which is made by Electronic Equipment Produktion & Distribution and uses an Intel Pentium M chip, can give drivers access to the Internet via 3G, Wi-Fi or 3GSM wireless networks."