I have been attmepting to tether my iPhone to my computer using bluetooth in Karmic.
Supposedy blueman can do this very easily (www.blueman-project.org). To install blueman just run:
$ sudo aptitude install blueman.
My experience with blueman has been very hit and miss however, the connection appears to be made via bluetooth but I can rarely seem to get NetworkManager to make a network connection. Sometimes I have success pairing the devices again.
Using the older pand binary I have had a lot more success. If you are not scared of the terminal, it isn’t difficult and appears far more reliable
Install the older bluez tools:
$ sudo aptitude install bluez-compat
$ hcitool scan
Find the address of your phone from the list
$ sudo pand --connect 00:25:00:96:13:BB -n
This command will pair you phone to your computer and create a pan device. Of course replacing the MAC address with the address of your phone. This command will re-pair you devices each time it is run. If, like me you have an iPhone, you need to have you iPhone in the Bluetooth System Preference app to accept the pairing.
$ sudo dhclient bnep0
You are now tethered.
To kill the tether:
$ sudo pand -K