popping up another contentpage from something happening in the viewmodel

Hi Experts,

I'm using the viewmodel as my controller. Not sure if that's a bad idea - but I don't know where else to put the control. When something happens in my viewmodel, I want to cause another page to pop up. What would you normally trigger in a viewmodel that would cause a page using it to launch another page? (Navigation.PushModal...)

Thanks for any help,
Mike