It's called the "Combox". I assume it's short for "Communication Box".
Excerpted from the Combox technical training manual:
Some of its functions include:
• Connection of audio players via Bluetooth
• Simultaneous connection of cell phones and audio players via Bluetooth
• Contacts with images
• Direct Bluetooth profile software update by customer
• Connection of certain iPods using the original USB cable
• Album cover display (for iPod, MTP players, MP3 via USB)
• Office SMS, calendar and notes from cell phone
• Office with email from cell phone
Combox technical manual posted from the F10 forum:
http://f10.5post.com/forums/attachme...9&d=1291578641
From RealOEM:
http://www.realoem.com/bmw/showparts...=84&fg=10&hl=9