Ever wanted to share the internet connection on your iPhone with your laptop/computer? Well and that too on the 
Note: If you are using iPhone with firmware 3.0 then you can tether it without jail breaking your iPhone by simply installing a modified carrier profile.If you are using iPHone with OS firmware 3.1.x then it needs to be jailbroken to installa the modified carrier profile.
To tether your iPhone 3G/3Gs on Ubuntu 9.10 via bluetooth, follow this simple tutorial and you will be able to do so in just a few minutes.
1. Install Blueman on Ubuntu
Tethering iPhone on Ubuntu is pretty much like simply pairing two iPhones. We need to install the bluetooth manager named Blueman from the blueman project PPA repository on the Ubuntu.
Run the following commands on terminal to install Blueman:
sudo add-apt-repository ppa:blueman/ppa
sudo apt-get update
sudo apt-get install blueman
If the installation was successful you can find the Bluetooth Manager in the System > Preferences menu.
2. Connect Ubuntu to iPhone
Once you have installed the blueman on ubuntu, turn on the bluetooth on your iPhone and make it discoverable and search for the devices on your ubuntu in the bluetooth manager program. This will list the nearby discovorable bluetooth devices including your iPhone. Locate your iPhone 3G/3Gs from the list and select it and pair with it.
Once your computer/laptop and iPhone are paired, press the diamond button on the Bluetooth manager.
3. Turn Internet Tethering ON on iPhone
Next step is to goto the following settings in your iPhone:
Settings > General > Network > Internet Tethering
and turn thetering on.
Now goto Bluetooth Manager program on your ubuntu and right click on the paired iPhone to select Network Access Point from the option Connect to. If it works out successfully it will give your a Connection Established message.
Now your iPhone is connected and ready to share the internet data connection with the Ubuntu 9.10 (Karmic Koala) using bluetooth.