Firefox 3.6.9 is a regular security and stability update to Firefox 3.6.x. The main focus will be to fix any OOPP issues found in the field and fix security issues after BlackHat.
Install firefox 3.6.9 in Ubuntu 10.04
Open the terminal and run the following commands
sudo add-apt-repository ppa:ubuntu-mozilla-security/ppa
sudo apt-get update
sudo apt-get dist-upgrade
This will install latest version of firefox.