Facebook will no longer allow FBML and FBJS for building apps!
“With our recent launch of Requests and the support for iframe on Pages Tabs, we are now ready to move forward with our previously announced plans to deprecate FBML and FBJS as a primary technology for building apps on Facebook. On March 11, 2011, you will no longer be able to create new FBML apps and Pages will no longer be able to add the Static FBML app. While all existing apps on Pages using FBML or the Static FBML app will continue to work, we strongly recommend that these apps transition to iframes as soon as possible. Lastly, we want to be clear that our deprecation of FBML does not impact XFBML, such as the tags that support social plugins.”