The new feature (Revit 2008 products) Duplicate View > Dependant Views is intended to provide an exact copy of the parent view but allow you to crop the view differently making it easier to document in an overall view but show partial plans on sheets. This makes it simpler to manage annotation and avoid the copy/paste process of putting annotation in various duplicate views.
Take care when you use the new feature (Revit 2008 products) Hide in View however.
If you use this feature either in a parent view or a dependant view the hidden element is only hidden in the view you do it in. The other view(s) are not affected. In my opinion, this is not consistant with the implied behavior of parent/dependant views. I believe that when we hide an element in a parent view, the dependant views should also have that element hidden. The view specific behavior should be limited to non-dependant views. As it is now, remember we must un-hide/hide this element in each view.