I paid a little more attention this weekend, and I noticed the noise occurs as the gauges fall to zero after turning off the ignition. At least one of the gauges must be gear driven (or gear reduced) instead of using a typical electrical meter movement.
i paid a little attention to it today. i noticed the sound and watched the gauges. the temp was lower than the fuel. when the temp was at zero, the noise got quieter. then when the fuel was at zero, the noise stopped. it is definatley in the gauges. i dont have the IUP, so i can only vouch for the two upper gauges in the cluster. i will mention something to the dealer next time i go in for something, but i am not worried about it.
if it bugs you so much, you are not getting out of the car fast enough!
Mine does it too, but if I'm not mistaken, I think it is the vacuum hoses making that noise when shutting the engine off. In any event, I wouldn't worry too much, I've heard mine doing it since I bought it on April 05