This works in firefox, and IE 9, but fails in IE 8 (shows both instead of just English):

<div lang='en'>

<h1 class='en-only'>English</h1>

<h1 class='de-only'>German</h1>

</div>

<script>

$(document).ready(function(){

$('.en-only:not(:lang(en)),.de-only:not(:lang(de))').hide();

})

</script>

http://jsfiddle.net/tvtds/