Руководство jQuery

    $("div span:last-child")
        .css({color:"red", fontSize:"80%"})
        .hover(function () {
              $(this).addClass("solast");
            }, function () {
              $(this).removeClass("solast");
            });

"HTML"

<div>
    <span>John,</span>
    <span>Karl,</span>
    <span>Brandon,</span>
    <span>Sam</span>
  </div>
  <div>
    <span>Glen,</span>
    <span>Tane,</span>
    <span>Ralph,</span>
    <span>David</span>
  </div>

"CSS"

  span.solast { text-decoration:line-through; }

"Живой пример jQuery"

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
						"http://www.w3.org/TR/html4/loose.dtd">
	<html>
	<head>
	<link href="http://test-drupal.ru/themes/slyweb/css/jqueryiframe.css" 
	rel="stylesheet" type="text/css"/>
	  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.0/jquery.min.js"></script>
	<script>
	  $(document).ready(function(){
	
    $("div span:last-child")
        .css({color:"red", fontSize:"80%"})
        .hover(function () {
              $(this).addClass("solast");
            }, function () {
              $(this).removeClass("solast");
            });



	  });
	</script>

	</head>
	<body class="iframe">

	
<div>
    <span>John,</span>
    <span>Karl,</span>
    <span>Brandon,</span>
    <span>Sam</span>
  </div>
  <div>
    <span>Glen,</span>
    <span>Tane,</span>
    <span>Ralph,</span>
    <span>David</span>
  </div>


	</body>
	</html>

	
	<style>
	
  span.solast { text-decoration:line-through; }

	</style>

Метод появился в jQuery 1.1.4 (http://api.jquery.com/lastChild/)

Версия jQuery 1.4.2 Документ создан 2010-08-21