title: The tag 'Interaction.Behaviors' does not exist in VS2010 (Blend 3)
body: <p>There seems to be a problem with support for the Interactivity namespace of Blend 3 in the VS2010 xaml editor. I have the following installed:</p>
  
  <ul>
  <li>VS2010</li>
  <li>Blend 3 + Blend 3 SDK</li>
  </ul>
  
  <p>I am trying to compile a demo project that is targeted at .Net 4 Client Profile and has a reference to System.Windows.Interactivity (in the Blend 3 folder).</p>
  
  <p>In the object browser everything appears to be fine. I can also access Interaction.Behaviours from code-behind, but if I put the namespace <code>xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"</code> in the xaml file and try to use it, the intellisense is blank.</p>
  
  <p>If I copy something in there anyway, the compiler says:
  <code>The tag 'Interaction.Behaviors' does not exist in XML namespace 'http://schemas.microsoft.com/expression/2010/interactivity'.</code></p>
  
  <p>Do I need to install Blend 4 RC or something?</p>