Mozilla sent Firefox Version 20 to the release channel. Included in the update are eleven (11) critical security updates. To get the update now, select "Help" from the Firefox menu at the upper left of the browser window, then pick "About Firefox." Mac users need to select "About Firefox" from the Firefox menu. If you do not use the English language version, Fully Localized Versions are available for download.
Additional information is available in Mozilla Firefox 20.0 Released With Critical Security Updates (http://securitygarden.blogspot.com/2013/04/mozilla-firefox-200-released-with.html).
Firefox 20.0.1 was released today. The primary reason for the update is to fix the problem many users experienced with the search bar being unusable (bug 846848 (http://bugzil.la/846848)).