Update 21 January, 2010: I removed the "pre-alpha" from the title, as now this PPA has the latest Firefox 3.6!

System > Administration > Software Sources

Third-Party Software

deb http://ppa.launchpad.net/fta/ubuntu UBUNTU_VERSION main

sudo apt-get install firefox-3.6

Firefox 3.6 alpha1pre in Applications > Internet under the name: Namoroka Web Browser

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 247510BE

You can also use this method to install Firefox 3.5

sudo apt-get update && sudo apt-get install firefox-3.5

Applications > Internet

Update 22 January, 2010:

Go to, to thetab and add this repository:Replacing "UBUNTU_VERSION" with Karmic, Jaunty, Intrepid or Hardy. Then click on Close, open a terminal and type: sudo apt-get updateThen, use this command in a terminal to install Firefox 3.6:After install is complete, you can findThen add the PPA Key:. After completing the steps above (only adding the repository and import the key), simply type this in a terminal:You will then see Firefox 3.5 under the name Shiretoko Web Browser inIt seems there's an error with the latest Firefox 3.6 and AppArmor (permission issues). See a fix, HERE