Mozilla has released the 18th update for Firefox 3.6 on June 21st. This update fixed several security issues & stability issues. See release notes for full details. Users can get the update by going to Help >> Check For Updates.
Support for Gecko 1.9.2/Firefox 3.6 will continue. Next release will be Firefox 3.6.21, with a release date likely to be around September 27, 2011. Firefox 3.5 has reached end of life support as of April 2011, depending on your operating system you should upgrade to Firefox 3.6 or 6.0