That's been out for a while. It's BMW's iPodYourBMW kit -
http://ipodyourbmw.com/
The drawbacks with this kit are:
- it doesn't work in vehicles with DSP
- it doesn't work in vehicles with Navigation
- it doesn't display ID3 song tags
In my opinion, the Dension IceLink Plus is a better solution. It provides total integration of the iPod into your X5 without the limitations noted above.