With the new Apple Mac Mini there have been a few installations in cars.
Here is one example in a VW Golf GTi.
Quite cool stuff, watch DVDs, play music through iTunes to your carstereo or directly to speakers from the computer. Download your camera when out driving to the computer. With a GPS antenna you can get navigation, a lot of stuff can be done with this. Hook up a G3 phone and you can surf to Lateral-G when out on thour!
http://tunertricks.com/blog/index.php?p=40
And for you that don't know what I am talking about
:
http://www.apple.com/macmini/
Cool stuff.
Jan