For Mark [1], who may or may not find this horrifying (he used to work on car diagnostic software, so he's had more than enough exposure to automobile based networks): BMW testdriving IP (Internet Protocol) as the underlying protocol for car computers [2] (link via Instapundit [3]).
[2] http://www.autoblog.com/2007/12/01/idrive-via-ip-bmw-uses-internet-protocol-underhood/