Twitter like next post load for Wordpress

Twitter like post load

<?php
add_action('wp_ajax_and_action', 'add_next_post');

function add_next_post()
{
  $query_string = $_POST['query_string'];
  $offset = $_POST['paged'] * get_settings('posts_per_page');
  $per_page = get_settings('posts_per_page');
  
  query_posts("$query_string&offset=$offset&posts_per_page=$per_page");
  
  get_template_part( 'loop', 'paginate' );
  
	die();
}

add_filter('wp_footer', 'javascript_page');

function javascript_page() {
  global $query_string;
  ?><script type="text/javascript">
    
jQuery(document).ready(function($) {


  var ajaxurl = '<?php echo home_url(); ?>/wp-admin/admin-ajax.php';
	var page_number = 2;
	var busy = false;
	
	$('.loading-more').bind('click', function(e) {
			busy = true;
			$('.loading-more').html('<em>Loading more posts..</em>')
			$.post(ajaxurl, {
			    action: 'and_action',
          query_string: '<?= $query_string ?>',
			    paged: page_number
			   	}, function(data) {
			   		if (data == '') {
			   			$('.loading-more').html('<strong>No more posts!</strong>');
			   		} else {
				   	  $('.empty-div').append(data);
				   	  	busy = false;
				   		$('.loading-more').html('<em>Load more posts</em>');
				   		page_number += 1;
				   }
			});
	});
});
</script>
<?php } ?>

// Add to index.php template
// <div class="empty-div"></div>
// <div class="loading-more span12"></div>

// twitter bootstrap