title: Phonegap doesn't show alert
body: <p>why phonegap doesn't show alert notification ? (running on iPhone 5.1.1 , phonegap phonegap-2.1.0-0-g26d211b, mountain lion 10.8.2, xcode 4.4.1)</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;link rel="stylesheet" href="themes/css/apple.css" title="jQTouch"&gt;
  &lt;script src="src/lib/zepto.min.js" type="text/javascript" charset="utf-8"&gt;&lt;/script&gt;
  &lt;script src="cordova-2.1.0.js" type="text/javascript" charset="utf-8"&gt;&lt;/script&gt;
  &lt;script src="src/jqtouch.min.js" type="text/javascript" charset="utf-8"&gt;&lt;/script&gt;
  &lt;script type="text/javascript"&gt;
      $(document).ready(function(){
       try
       {
          navigator.notification.alert('Hello', ok, 'Title', 'Button!');  
       }
       catch(e)
       {
          alert("doesn't support!!");
       }
      }
      function ok() {}
  &lt;/script&gt;
  &lt;/head&gt;
  &lt;/html&gt;
  </code></pre>