Mozilla released Firefox 4 Beta 11 and available for download through its FTP servers. Mozilla planning to release yet another beta after this. Currently this beta release is being distributed to mirror sites, once the distribution is complete you can read Official  announcement on Mozilla’s blog.

Firefox 4 Beta 11

This release allows users to Opt-out of the ad Tracking.

Read Try “Do Not Track” HTTP Header for Firefox Browser Now

Firefox 4 Beta 11 release notes

Download Firefox 4 Beta 11