Using iframes in Page Tabs
Many useful applications have been built for Facebook Pages like BandPage for artists to share their music with fans and Shop Now to help Pages sell merchandise on Facebook. As of today, you can build your Page Tab apps using iframes rather than FBML. This means you can now build apps that run across Facebook (including Pages and Canvas applications) using the same simple, standards-based web programming model (HTML, JavaScript, and CSS). In addition, you can easily integrate social plugins and the Graph API within your tab.
FBML Roadmap
FACEBOOK is now ready to move forward with their 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.
SOURCE:facebook developers
