Yes, PAC makes an adapter called the Ipod2car which uses the factory CD Changer input.
EDIT: Dammit I always mess that up. Sorry, Ipod2Car is by PERIPHERAL electronics. PAC makes a SIMILAR solution.
The expensive ones (180 or so) allow CONTROL of the ipod via the headunit... the cheaper ones simply hijack the XM or CD Changer input for audio only, but dont power your pod.
EDIT: Dammit I always mess that up. Sorry, Ipod2Car is by PERIPHERAL electronics. PAC makes a SIMILAR solution.
The expensive ones (180 or so) allow CONTROL of the ipod via the headunit... the cheaper ones simply hijack the XM or CD Changer input for audio only, but dont power your pod.