Mozilla have released Firefox 3.0.12. It is a security/stability updates, for more details see the Firefox 3.0.12 Release Notes
Firefox 3 will be supported with security/stability updates until January 2010

Note: This update is not for Firefox 3.5 users.
If you are using Firefox 3 and want to upgrade to Firefox 3.5, it is available from http://www.mozilla.com/