I have ANYSTREAM device that connects to my iTouch/iPhone cradle in my Jetta. The device works as: manually connect it, find it on your phone via Bluetooth and connect, play some music... say Pandora, and it will stream to your headunit the same as you would be listening to your iTouch device.
However, on my Jetta it didn't work. The late owner of the company foretold me that in certain cases, the device doesn't work-yes unfortunately the owner deceased, and the company closed. My cousin has one and it works both on his MB S class, and his honda; he loves his.
There is another device called Coostream. Works the same way. I'm kind of tempted to buy one for the Jetta.
I hope this is what you are looking for.