I couldnt be bothered waiting and use the following and it is a great solution!! Had the i-pod Icelink for the Mini and the sound was no different in terms of quality.
I have the iTrip mini currently. It is not perfect, although it is far better than carrying a bunch of CDs around. The main problem is it is low fidelity: only 45dB of signal separation and it only transmits 50Hz to 15kHz. So any music you've listened to directly from the CD with even mediocre equipment will reveal the iTrip's shortcomings. Basically the high end is murky since nothing above 15kHz is produced. The inadequate quantity of signal separation means that there is a fair amount of hiss at low volume that never goes away with higher volumes. And of course you lose an entire octave of bass with the 50Hz cutoff. However, it is very good about letting you pick any channel between 87.9 and 107.9 MHz and its integration with the iPod is seamless. I simply wish there were a more "audiophile oriented" FM modulator. If I could get 20Hz-22kHz and about 70dB of separation, even at the expense of battery life, I'd do it. If anyone is aware of such a product, please post it so I can check it out.
From what I remember about FM, the best theoretical bandwidth you could get would be 19kHz (half the difference signal carrier) - with real world filters 17-18kHz would probably be as good as you would get without compromising other areas.
The 70dB separation could be achievable, but only if the FM receiver would support it - which I doubt most car units would. Most car units would also limit the bandwidth to 15kHz.