Windows/Mac/Linux: The latest version of Firefox, Firefox 21, is officially due tomorrow, but you can download it now from Mozilla's FTP servers. What will you find in this new release? A few major new features, including three "Do Not Track" options, a tune-up tool called Firefox Health Report, and performance-boosting startup suggestions.
The "Do Not Track" update adds options beyond the single checkbox for opting out of advertiser tracking: "Do Not Track", "Track" and "No preference". The Firefox Health Report is, as the name suggests, a troubleshooting tool to display performance information about the browser. Firefox will also offer suggestions for improving the program's startup time.
The beta version's release notes also reveal various performance improvements and fixes. PCW orld also notes that Firefox will have an expanded social API for better integration with Facebook and other social networks.
All in all, it looks like a significant update. Here's the link to the download again, if you can't wait until tomorrow: