Today mozilla released the latest version of firefox V 12.0 for Windows as well as Linux and Mac users.
There are no much visible changes in the latest vesion. Only some UI changes and performance improvements are there.
The background updation of firfox makes its painless. It will download the latest version in the background and will
update the previous version without any user interaction.
If you don’t have a previous version installed on your system, you can grab the latest version of Firefox from here