Referring to Facebook Developer Roadmap on FBML Deprecation,
FBML apps will no longer work on Platform. All FBML endpoints are removed as of June 1, 2012
Some people may wonder if the XFBML code that their have used for Facebook Social Plugins will continue to work after the FBML endpoints are removed.
The answer is simply “Yes”.
Having said that, if you are to add new social plugins to your websites or applications, then the HTML5 version is strongly rec0mmended.