Get ready for a new development milestone of Mozilla’s next iteration open source browser ahead of the Release Candidate Build. Although it was initially planning to make available a single Beta on the way to RC, Mozilla is now preparing to offer early adopters of Firefox 3.6 the forth Beta release. In this context, Mike Beltzner, director of Firefox at Mozilla, has announced that the almost half a million Firefox 3.6 Beta testers will be served the Beta 4 Build ahead of graduating the next version of the open source browser to RC stage.

Testers interested in getting on the Firefox 3.6 Beta 4 early need to know that Mozilla has already published the bits on its FTP servers. Users unfamiliar with Mozilla’s development process for Firefox should know that the candidate bits available for download are not the final Firefox 3.6 Beta 4. Mozilla will most probably release the fully-fledged Firefox 3.6 Beta 4 to all testers in the coming days, although a specific availability deadline was not specified as of yet.

Mozilla indicated that as of the start of this week the number of testers running Firefox 3.6 Beta 4 had jumped over the 450,000 milestone and was making its way to half a million. The third Beta Build of Firefox 3.6 was offered to testers last week and is the latest development milestone suited for public release, and not just a nightly Build.

“As discussed in today's development meeting, due to the excellent work on knocking down the Firefox 3.6 Beta topcrash list, we've decided that it would be worthwhile to ship another beta update to our close to half million testers to confirm our expectations. We'd also like to get as much feedback as possible on the more than 140 fixes we've made since we shipped the update last week,” Beltzner added.

According to Mozilla’s Director of Firefox, Beta 4 of Firefox 3.6 is just around the corner. “If all goes well, we'll look to ship updates to our beta users late Wednesday or early Thursday; either way, it will be up to those outside the USA to drive it over the line, as our American friends enjoy their well-earned Thanksgiving holidays,” he noted.

The latest release of Firefox 3.6 Beta is available for download here.