Steps to reproduce.

1) load ajax via .ajax() method

2) put in dom via (id).html(ajax_result);

The following example works:

ajax_result =

<a href="#">hello</a>
<script> 
    alert('I will execute');
    $(document).ready(function(){
         $("a").click(function() {alert('hi');});
    })
</script>

Howerver, this example does not:

ajax_result =

<div>
<a href="#">hello</a>
<script> 
    alert('I will execute');
    $(document).ready(function(){
         $("a").click(function() {alert('hi, but you won\\'t see me');});
    })
</script>
</div>

Notice that the only difference is that one binding happens inside of a parent element.

I've tested this behavior in IE 7 and FF 2.0.0.8

I'm not sure if this behavior be expected to work as it's generally recommended to leave javascript out of the body of a document however sometimes it's necessary.