Few days ago the final version of Firefox 4 come to life.
With this guide I will show you how to install Firefox 4 on Ubuntu and its variants with the official repositories.
Open a terminal and add the Firefox’s repository:
sudo add-apt-repository ppa:mozillateam/firefox-stable
Than update the package manager’s database:
sudo apt-get update
If you already have Firefox, you can just give the upgrade command:
sudo apt-get upgrade
Otherwhise you can install Firefox 4 with the following command:
sudo apt-get install firefox