Just a little snippet I worked up that may be useful to someone …

jQuery(document).ready(function($){
$('div#checkall-wrapper input[type=checkbox]').click(function(){
	if( $(this).attr('checked') ){
		$('tdiv#wraparound-targets input[type=checkbox]').attr('checked','checked');
	}else{
		$('div#wraparound-targets input[type=checkbox]').removeAttr('checked');
	}
});
});

Make sense?