Griffin, one of my favorite iPod/iPhone/Accessories maker just released iTrip Universal, a new FM Modulator designed to work universally across all music/PMP/video/audio/cd players. So long as you have a 3.5mm jack, you can take advantage this new gadget.
The iTrip universal has a built-in rechargeable battery so it would not drain your device anymore than playing back. It has an easy to use interface allowing you to playback your favorite tunes in the best available station (easily changes stations and allows up to three presets). With a backlit LCD, this is handy in all lighting conditions.
With a product like this, I think it goes beyond automobile; anyone with a radio can now enjoy playing music from any device (ie. smartphones, mini-disc player, laptop, etc.). The next time you go to a party, something like this can let you playback your favorite tunes over any stereo system.