Firefox 21 is due to officially launch on Tuesday, but you can grab the desktop version now from Mozilla’s servers here: FTP.
If you prefer to wait for the official launch, keep your browser pointed to Firefox.com. Soon after it arrives tomorrow, Mozilla will also push it out via the browser’s automatic updates.
There’s no official Firefox 21 changelog as of yet, but the beta release notes should serve as a decent guideline (remember that features are sometimes added or removed before the stable version is released):
It's happened to everyone -- you visit a Web site and instead of the browser taking you directly to it, you get a notice that says you're about to visit an untrusted site. The reason this happens is because the browser hasn't certified the site.
This type of action could mean a slow death for such a Web site, since messages like these tend to scare off users.
Mozilla has added automatic third-party cookie-blocking to a preview version of Firefox 22, a move that will put the feature in most users hands by late June and the company on a collision course with the online ad industry.
Advertising trade groups have blasted the new cookie blocking, calling it "dangerous and highly disturbing," and promising that Firefox users would see more online ads as a result.
Mozilla has released Firefox 20 FINAL for Windows, Mac and Linux, and version 20 promises to be something of a landmark new release with a number of notable new features migrating across from the beta version.
The headline new feature has to be the long-awaited panel-based download manager, but Firefox 20 also debuts per-window Private Browsing, plus new developer features including an option to view Developer tools in a separate window to Firefox itself.
Mozilla has begun to experiment with a new patch for Firefox, which changes whether cookies from third parties are allowed.
Citing Safari as its driving force behind the new approach, the patch will require users to "directly interact with a site or company for a cookie to be installed on their machine".