As soon as iPhone 3.0 software comes out (I have been playing with the Betas) which has A2DP I plan on hiding my aux in location and connecting one of these:
Anycom BAR-10 Bluetooth Audio Receiver : Home Electronics(8270) : Speakers & Subwoofers : Misc.
Right now I have the wire coming out underneath near the center console and then it comes up by the seatbelt area, but once I have A2DP and bluetooth hooked up, should be able to just hop in the car and play music wirelessly.