I am in a similar position to egggman. Here is my current steup:
-Thinkpad X200 with bluetooth and Ubuntu Intrepid
-Blackberry 8120 with T-Mobile
I have installed barry using Martin Owens' Ubuntu PPA repository. Using barry I am able to connect to the 8120 using USB: sudo pppd call barry-tmobileus However, I am only able to use the data connection for a short period of time. After this it no longer seems to work.
My goal is to tether over bluetooth and have a connection that works for longer than a few seconds.
If a set of steps are posted I can try with my setup and help debug. I have played with barry and hcitool. I'm just not sure where to proceed from here.
Any additional details, links, or suggestions would be appreciated.