A short time ago, Firefox released the latest stable version of Firefox 3.0.
If your browser doesn't automatically update, you can simply click 'Help' (at the top), then 'Check for Updates'.
This latest release comes a few days ahead of schedule and addresses a variety of security issues, stability issues, and fixes a number of reported bugs.
The complete list of release notes can be found here
Note: As of this post, the page above says 'Beta' which appears to be a typo, as an update had been expected and Firefox 3.0 went final some time ago. All extensions (that we use) are working fine.
Progress continues on the next significant release of Firefox (still in the 'Minefield') with a host of features and improvements being tested in the nightly builds of Firefox 3.1 RC2.