I couldn't find any decent looking iPhone car chargers (decent is defined as: small, unobtrusive, and not ugly), so I went the easier route. It ended up being a lot cheaper too ($50).
I bought a cheap ($50) 200 watt power inverter and mounted it with velcro behind the dash. I plugged the included iPhone dock into the inverter using the power brick charger and plugged the stereo's "line in" cable to the "line out" port on the dock. Instant digital audio and charging capability for not a lot of work. In the event of a call, the phone rings through the car speakers and then pauses the music when you answer. It's also easy to remove the dock and leave the cables if you need to (worried about theft, etc.). Pictures linked to Flickr for larger versions:
I bought a cheap ($50) 200 watt power inverter and mounted it with velcro behind the dash. I plugged the included iPhone dock into the inverter using the power brick charger and plugged the stereo's "line in" cable to the "line out" port on the dock. Instant digital audio and charging capability for not a lot of work. In the event of a call, the phone rings through the car speakers and then pauses the music when you answer. It's also easy to remove the dock and leave the cables if you need to (worried about theft, etc.). Pictures linked to Flickr for larger versions: