A few months ago, I was in a forum where someone realized Apple had put the same headphone jack that is on the old iPod into the 800MHz iBook. It is not a standard flush jack, but a one with a small outer ring around it. Just out of curiosity, I plugged the iTrip into my 800MHz iBook and noticed the power LED lit up. I started an iTunes song, turned on the home stereo and was getting sound from my iBook transmitted with the iTrip. Way cool.
iTrip used with iBook