The first Release Candidate for Firefox 3.5, formerly version 3.1, is as close to availability as possible, reveals Mozilla. The next iteration of the open source browser is on the verge of evolving from Beta to RC. However, although downloads are just around the corner, Firefox 3.5 is not live yet.

The best that users can hope for, at least for the time being, is to grab a pre-RC nightly build. And while Mozilla is gearing up to take Firefox 3.5 RC out of the baking oven, it is also cooking another test day for the browser.

“I'm here to inform that we're going to be holding another Fx3.5 RC1 Testday event on Friday, June 5th, from 7AM - 5PM PDT! It'll be a concentrated mozQA Community day committed to testing Firefox 3.5 RC 1. This time around we should have the real builds out this Friday,” revealed Aakash Desai, QA Engineer at Mozilla Corporation. “MozQA is holding a Testday for the rollout of Firefox 3.5 RC 1 which is as close to a release as possible! I don't need to remind everyone of how important this phase is, so we're going to need your awesome testing skills to make sure its as polished as possible.”

It now appears that users will be getting Firefox 3.5 RC1 ahead of Firefox 3.0.11. Mozilla identified a regression issue with the latest security and stability update for Firefox 3.0, and postponed the release to a date yet to be announced. By contract, on June 3, 2009, there were only two blockers left for Firefox 3.5 RC1.

Blockers are generally referred to as show stopping issues, bugs severe enough to prevent the browser from advancing to the next stage in its development process. Mozilla estimated a couple of days ago that it would have resolved all Firefox 3.5 RC1 bugs by today, June 5. At the same time, Mozilla indicated that anticipation for RC1 was great, with over 800,000 users running the Beta 4 development milestone of Firefox 3.5.

Firefox 3.5 Beta 4 and Firefox 3.0.10 for Windows are available for download here.

Firefox 3.5 Beta 4 and Firefox 3.0.10 for Linux are available here.

Firefox 3.5 Beta 4 and Firefox 3.0.10 for Mac OS X are available here.