you got me paranoid about the heat issue, so i decided to do some testing.
i started up itunes, loaded a big playlist and started it.
then i turned my LCD brightness all the way down so it turns off.
then i closed the lid but put a small wedge in to keep it just 1/4" open so it would remain awake.
then i let it play for an hour.
it played fine and never got too hot, so i think it will work out ok... i'm just going to fashion a better wedge and attach it somehow so it won't fall out when i'm in the car.
i'm also trying to think of a clever way to make a sleeve for the tiBook that hangs under the dash in the passenger seat... if it works out i'll take a pic and post it..
-bret