[Sigizmund2012]

<div class="comment" id="comment512">
  <div class="content">
    text
  </div>
  <div class="comment512_answer"></div>
  <a href="#" class="answer">
    rep
  </a>
</div>


<script>
$(document).ready(function(){
  $("a.answer").click(function(){
    var div = $(this).parents(".comment");
    var selector = '.' + div.attr('id') + '_answer';
    $( selector ).load('block.php');
  });
});
</script>

Содержимое моего block.php:

<?php 
	echo "My supercomment";
 ?>