Firefox 3.6 is the latest major version of Mozilla Firefox which was released on January 21st, 2010. This article describes how to upgrade to Firefox 3.6.
If you use your Linux distribution's packaged version of Firefox, you will need wait for an updated package to be released to its package repository.
If you installed Firefox manually (without using your distribution's package manager)To upgrade to Firefox 3.6, you need to be using the latest update to Firefox 3.0 or 3.5:
For more information, see Update Firefox to the latest version.
The following articles may be able to help:
Most changes in Firefox 3.6 are improvements to stability and performance.