That was fast. We just learned Magellan was going to offer a car kit for the iPhone and it has already hit the FCC. GPSTracklog.com has a detailed drawing of the new device, and it looks to be quite complete. Magellan has said the kit will be on sale before the end of the year, and even give the iPod touch full nav capabilities.
The car kit is supposed to allow any iPhone GPS app to work with it, so you're not limited to the Magellan app. It works in portrait or landscape mode, and has a speaker for hearing directions and also link to your iPhone for Bluetooth based calls.
The Magellan Roadmate app itself [iTunes link] has a boatload of good features, and we're anxious to get our hands on the app for a full test. Holiday travelers will have a lot of good choices for navigating to your destinations. Remember when we thought the plain old Google Maps app was cool?
Thanks to Rich for the tip.