I have found iPhone compatibility for accessories spotty at best, and you often cannot tell from the vendor's website or packaging. My FM transmitter (a cheap Newtech) does not work with the iPhone, but worked perfectly with my 1G nano. My griffin PowerBlock only works with the iPhone if the battery is not in the red zone (but Griffin says it is compatible); again it worked flawlessly with the nano. Even if the iTrip did work it may well be unusable because of gsm noise. I have all but quit using my iPhone for music and instead bought a 2G shuffle. The idea of a converged devices was great, but the implementation leaves a lot to be desired. If it were not for the stupid 2-year contract I would probably go back to a separate phone and iPod.
