title: When to dispose ViewModel in MVVM Light
body: <p>I'm looking into getting started using MVVM Light, and I came across the "new" ICleanup interface. I was just wondering when would you cleanup the VM...when you navigate away from the page?</p>
  
  <p>Also, I see there is a Main Cleanup in the ViewModelLocator which should cleanup all the VM's...when would this be used?</p>
  
  <p>Thanks very much</p>
  
  <p>Regards,
  Mauro</p>