$.fn.initFbComments

fiddle.css

.mod-fbcomments{
    float:left;
    margin:5px;
}

fiddle.html

<script src="https://raw.github.com/SlexAxton/yepnope.js/master/yepnope.js"></script>
<button id="button">Boom</button>
<div id="root"></div>

fiddle.js

var src = [
	'<div class="mod-fbcomments"><fb:comments href="example.com" num_posts="1" width="250"></fb:comments></div>',
	'<div class="mod-fbcomments"><fb:comments href="yahoo.com" num_posts="1" width="250"></fb:comments></div>'
].join('');

$.fn.initFbComments = function(){
	var found = false;
	this.each(function(){
		if( $('.mod-fbcomments', this).size() !== 0 ){
			found = true;
			return;
		}
	});
	if(found){
		yepnope.loader.load('http://connect.facebook.net/en_US/all.js#xfbml=1')
	}
	return this;
};

$(function(){
	var $root = $('#root');
	$('#button').click(function(){
		$root.empty().append(src).initFbComments();
	});
});

fiddle.manifest

name: $.fn.initFbComments
description: append facebook comments dynamically. http://jsfiddle.net/gh/gist/jQuery/1.6.2/1173316/ https://gist.github.com/1173316 http://developers.facebook.com/docs/reference/plugins/comments/
authors:
  - Takeshi Takatsudo
normalize_css: no