The early models even had free unlimited worldwide 3g connectivity. Which of course was too expensive for such a cheap device, but shows that offering car connectivity really can't be so costly.
Still free on the new 3g enabled models. But when you say 'free' it only allows you to browse Amazon and buy Amazon books so they just build the costs into those... So thanks to everyone who buys eBooks on Amazon and funds my Kindle DX's 3g connection :)