title: Reactive Extension (Rx) tutorial that is up to date
body: <p>I am quite interested in Reactive Extensions but I cannot find an up to date tutorial. I started with <a href="http://go.microsoft.com/fwlink/?LinkId=208528" rel="noreferrer">Curing the asynchronous blues with the Reactive Extensions for .NET</a>  but it is out of date. I can figure out some changes but I could not get many examples working.</p>
  
  <p>I found many articles on the web, mainly from 2009,2010 but they are also incompatible with the current release. I am especially interested in using Rx with Windows Phone and WebClient:</p>
  
  <pre><code>WebClient wc = new WebClient();
  
  var o = Observable.FromEvent&lt;DownloadStringCompletedEventArgs&gt;(wc, "DownloadStringCompleted").Select(newString =&gt; newString.EventArgs.Result);
  
  // Subscribe to the observable, and set the label text
  o.Subscribe(s =&gt; myLabel.Text = s);
  
  // Start the download
  wc.DownloadStringAsync(new Uri("http://www.data.com/service"));
  </code></pre>
  
  <p>Do not work anymore and replacing <code>FromEvent</code> with <code>FromEventPattern</code> is not enough.</p>
  
  <p>Can somebody point me to an up to date resource?</p>