PPA para Firefox 3.6 [Ubuntu]

sudo add-apt-repository ppa:mozillateam/firefox-stable

para versiones anteriores a karmic:

sudo bash -c "echo 'deb  http://ppa.launchpad.net/mozillateam/firefox-stable/ubuntu  UBUNTU_VERSION main' >> /etc/apt/sources.list" && sudo  apt-key adv --keyserver keyserver.ubuntu.com --recv-keys CE49EC21

sudo apt-get update && sudo apt-get install firefox-3.6

via: [ElectroBuntu]