block.fbml.php

<?php

function smarty_block_fbml($params, $content, &$smarty, &$repeat)
{
    if (!$repeat && !empty($content))
    {
        $content = trim($content);
        $output = <<<EOT
<fb:serverFbml>
    <script type="text/fbml">
        <fb:fbml>
            {$content}
        </fb:fbml>
    </script>
</fb:serverFbml>
EOT;
        return $output;
    }
}

example.tpl

{fbml}
<fb:application-name></fb:application-name>
{/fbml}