According to the download page for Firefox 3.5, Mozilla has already killed off this browser version.

Users visiting the site that allows them to grab the previous iteration of Mozilla’s open source browser are welcomed by a message noting that August 2010 was the last month in which the browser vendor supplied security and stability updates for the predecessor of Firefox 3.6.

“Firefox 3.5.x will be maintained with security and stability updates until August 2010. All users are strongly encouraged to upgrade to Firefox 3.6,” reads the message from Mozilla. (emphasis added)

Obviously, this is not the case. August 2010 has come and gone, but Mozilla is hard at work on the next stability and security update for Firefox 3.5.

In fact, as I said just a few days ago, early adopters can download and start test driving the Beta Build of Firefox 3.5.12, along with a pre-release development milestone for Firefox 3.6.9.

rest here