I just received this info from Crutchfield.

It's called the USA SPEC iPod® Interface Crutchfield Product Link


Details:
» iPod connection adapter for select BWM factory stereos
» manage the iPod via your radio's CD changer controls
» adjust volume, track up/down, fast forward/rewind
» use up to five playlists (select five favorites, or Auto Playlist will let you choose from the first five on your iPod)
» Direct Mode allows you to control everything via the iPod itself, giving you access to all playlists (requires a DIP switch change on the USA SPEC adapter)
» compatible with all iPod and iPod mini models equipped with a dock connector and iPod software update 2004-04-28, or higher
» warranty: 3 years

What you need to know :
» Factory radio must NOT have DSP (Premium Sound).
» You will need to disconnect the factory CD changer, if you have one, and connect the new adapter in its place.
» Adapter plugs into the factory cable.
» Factory cable is in the trunk.
» The Crutchfield MasterSheet, if available, does not cover OEM integration.