Finally Mozilla Firefox team has Officially release Firefox 6 Final trough this announcement and has been putted in mozillateam PPA, for those ubuntu user who have not tried yet, can Install/Upgrade to Firefox 6 through this way.
Mozilla Firefox 6 Final
Upgrade / Install Firefox 6 via PPA
Follow this step to upgrade/install Mozilla Firefox 6 Final to ubuntu :
  • sudo add-apt-repository ppa:mozillateam/firefox-stable
  • sudo apt-get update
  • sudo apt-get dist-upgrade

Mozilla Firefox 6 final also available for download via Mozilla Firefox FTP, which usually released ahead it's official release.

Now Firefox 6 Final has available in ubuntu 11.04 default repository, go to terminal then type apt-get upgrade firefox. (you do not need to use PPA repository to install/upgrade Firefox 6 in ubuntu).