Install firefox4 Beta in ubuntu

Firefox 4 beta 6 is already available for Linux, Windows and Mac. You can also install daily builds to get the latest of Firefox. The PPA ubuntu-mozilla-daily provides the daily builds of Firefox, currently beta 3 is available for download. 


or from terminal


sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa && sudo apt-get update

sudo apt-get install firefox-4.0