Apple and BMW announced that BMW owners can play their iPod on their stereo. Engaget has a good review on this, and I agree with it. I think that this product will be cool, once the iPod UI is shown on the head unit itself. Ideally, I think that it would bew great if the head unit had a motorozed slot that took in the iPod.
I think that Alpine could do a good job if they do what they announced at CES. Alpine already has the ability to have a ui from components on their head units. For example here is a picture of their hda-5460.