In the previous post we told you how to install firefox beta version on Ubuntu. Before couple of days firefox 4 stable version has been released. To check out the new features of Firefox you can go to mozilla’s website.
You can install the latest version of Firefox via apt on Ubuntu.
If you have installed development version of Firefox then first remove it.
sudo apt-get remove firefox-4.0
Then add Firefox stable repository
sudo add-apt-repository ppa:mozillateam/firefox-stable
Update repository
sudo apt-get update
Now you need to install Firefox via apt,
sudo apt-get install firefox
After installation, you will find Firefox under Applications > Internet > Firefox Web Browser.
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My name is Vidyadhar Sarmalkar & I work as a consultant and have done RHCE & CCNA. 
RcruU4 Very true! Makes a change to see someone spell it out like that.