For you non-BMW owners out there...
...and that list includes myself, we find this nice little solution:
Alpine: iPod interface coming this fall
Apple and BMW's recent "iPod Your BMW" promotion offers a way for owners of recent-model BMW vehicles to interface their iPods with their stereos. But if you don't own a BMW or don't have a compatible model, what are you to do? One solution comes from venerable car audio maker Alpine, which in January announced the development of its Interface Adapter for iPod. With Apple and BMW's recent announcement making the rounds, Alpine recently offered further information about its product, which it now says will ship in the fall. [MacCentral]
I've been debating replacing the sub-par radio system in my Lancer, and this looks like a very viable candidate.