On its site, Mozilla wrote:
"Firefox 2.0.0.x will be maintained with security and stability updates until mid-December, 2008. All users are strongly encouraged to upgrade to Firefox 3."
Firefox 2 received its most recent update just last week, at the same time Firefox 3.0.4 was released, which addresses several security flaws. There will only be one more Firefox 2 update.
For all the hoopla surrounding its record-breaking release earlier this year, Firefox 3 has it critics, who claim the browser crashes too often and uses too much memory.
When support for Firefox 2 ends, so will support for its underlying Gecko 1.8 layout engine, which also underpins the Thunderbird e-mail client, as well as several Gecko-based browsers. According to ZDNet, Mozilla will continue support for Thunderbird, but the browsers will likely have to rely on third party developers.