Getting 3G in Ubuntu to work is pretty straight forward for most people but there can be some minor issues that affect a few of us especially if you are running Hardy Heron.
Firstly you'll want to go to https://forge.vodafonebetavine.net/projects/vodafonemobilec/ to get the Vodafone Mobile Connect Card Driver. At the time of writing this the latest stable version is 1.99.17.
Go to where you have downloaded the Deb file and Right-Click on it then select Open with "GDebi Package Installer" and install the package. The Package Installer will download and install any dependencies that are required and then it will install the driver.
Once the install is complete plug in your 3G device and give it about 30 seconds to register itself with the system. Now go to Applications -> Internet and select Vodafone Mobile Connect Card driver for Linux and the application will start up. A warning message stating that Device setup not completed click close on the message and confirm that the device it discovered is correct then it will ask for your pin number. It will then start the Authenticating process.
Now for most people this should be working now if not carry on reading.
If after selecting your device you just have a window with a progress bar bouncing back and forth then click Cancel and follow these steps:
1. Remove your 3G device
2. Run sudo udevcontrol reload_rules
3. Plug your device back in and wait about 30 seconds
4. Run the Vodafine Mobile Connect application again
It should now start the Authenticating process and go through successfully. Just note that this can take up to 1 minute sometimes.