Goodbye FBML Pages
Back on Feb 11, 2011 Facebook announced on its Developer Blog that as of March 10, 2011 you will no longer be able to create new FBML (not to be confused with XFBML) pages on Facebook. All new pages will be required to utilize iframes, which has been around for a while now.
Who does this affect: A lot of people. Static FBML has previously been one of the most utilized apps for Facebook page developers to publish a quick tab on their pages. The functionality wasn't great, but it was pretty easy and a lot of people took advantage of that.
While the change will not 'turn off' existing FBML tabs, Facebook does "strongly recommend that these apps transition to iframes as soon as possible." With the recent updates giving the axe to a lot of previous FB functionality, it is a distinct possibility that the existing FBML pages will get phased out as well sooner or later.
FBML Roadmap
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.