Only a short time ago, we had to wait over a year for a major new release of any web browser. Often longer. There was a huge gap between Firefox 3 and Firefox 4, with many alphas, betas and numerous release candidates. That was before Google changed the game with Chrome, with rapid releases, quickly switching between stable, beta, dev and Canary.
Recently, Mozilla decided to change the way they would release a new version of Firefox, somewhat mimicking the Chrome release schedule. You can now download this stable version of Firefox, currently v14, from this page, while adventurous users can also check out v15 Aurora and even v16 of Nightly, Firefox's "Canary" build, reserved for the most foolhardy.
What's new in Firefox 14? New features include support for Firefox within Windows 8's new Metro interface, desktop apps and a panel-based download manager. Landed features, including the inline auto-complete feature, are less visible, behind-the-scenes in nature.
Note that Firefox 14 is now final and in the stable channel.
Firefox 14 is the first version designed specifically for Windows 8 with support for the new Metro UI.