New Post: Prism 4.1 missing InvokeCommandAction?

I'm trying to use the new InvokeCommandAction as noted in the release notes and this workitem:

http://compositewpf.codeplex.com/workitem/5495

When I try to use the example XAML I get the error:
Error 33 The tag 'InvokeCommandAction' does not exist in XML namespace 'http://www.codeplex.com/prism'.

• I have updated my project references from Prism 4.0 to Prism 4.1
• I can implement the new ClearChildViewsRegionBehavior so I'm assuming my references are good
• Intellisense for <prism: ... /> in XAML shows the following:
  • ClearChildViewsRegionBehavior
  • InteractionRequestTrigger
  • RegionContext
  • RegionManager

Code example (copied directly from the workitem):

... user control and other namespace code
            xmlns:prism="http://www.codeplex.com/prism"        
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity>
  <StackPanel>
    <TextBox>
      <i:Interaction.Triggers>
        <i:EventTrigger EventName="KeyUp">
          <prism:InvokeCommandAction Command="{Binding MyCommand}" />
        </i:EventTrigger>
      </i:Interaction.Triggers>
    </TextBox>

... rest of view code