For those that are interested, here's another iPod interface that lets you control it through your factory radio. It's made by Monster (should be great quality). The great thing about this interface is that it lets you add an optional small lcd screen to display the track information.

Monster iCruze

The only downfall I see to this module is that you can't control the ipod directly when it's plugged in.

 

I haven't checked their site recently due to the fact they haven't designed one that's comapatible for the 3G models (Navi, XM). Do they have one now?

 

I'm assuming that this one isn't different than any of the other adapters. All you would need is a y-adapter such as the one from P.I.E. to retain your XM functionality.