I've done it. And it was about 2 years ago, so it was working even back then. Unfortunately it was about 2 years ago, and on a different system, so I don't really remember all the steps. I do remember that it was not that hard, and there are instructions on the web. You have to use hcitool to find the MAC address of the phone, and rfcomm for initializing the connection. More specific than that I forget. A quick google search for "gprs bluetooth linux" should get you going.
It's cool, I was listening to streaming internet radio in my car.
I hope this helps. Don't give up. It does work!!