FBML apps will no longer work on Platform. The "FBML Removal" migration will appear and will be enabled for all apps. It will be possible to disable the migration, thereby re-enabling FBML, until July 5, 2012 when the migration and all FBML endpoints will be removed completely.
Apps connecting to Facebook's XMPP service will be required to use STARTTLS for all connections. We will start rejecting unencrypted connections.