How Can I add a Hierarchical taxonomy Select in views filters and when editing content in Drupal 7
Response is late but I think(/hope) accurate. You can use the "Simple hierarchical select" http://drupal.org/project/shs. With the help of this module you can make use of the hierarchical select functionality both through views->exposed filters and of course when adding content. 


  The widget is available in node forms and as Views exposed filter.