Support for Firefox 2, which includes security and stability patches, is scheduled to end six months after Firefox 3 shipped (June 17, 2008), which puts the end-of-life date in the mid-December range.
[ SEE: Talking Firefox security with Mozilla’s Window Snyder ]
Mozilla has not yet set a final date for Firefox 2 end-of-life activity but the open source group has started discussing the "requirements or issues" that would force a deadline extension. The current plan is for the next Firefox 2 patch to the final update of that version.
According to Mozilla's Mike Beltzner, only about one-third of Firefox users are running older versions of the browser.
Firefox 3 is considered a major security improvement over Firefox 2 because of the addition of an anti-malware blocker and improved Web forgery warnings.
ALSO SEE: Browser Wars 2.0: Firefox scrambles to add ‘private mode’ browsing