This is really very subtle but with 2010 if you should happen to start with the really "dumb" template called "none" the pan/zoom functions don't work unless you have something in the view. This might makes sense except I wanted to turn on the new Project Base Point and Survey Point graphics and then Zoom to Fit. Revit won't Zoom to Fit or pan for that matter if they are visible when nothing else exists in the view.
If you add some text, a wall segment, an elevation view, a line...something pan/zoom come back to life. Apparently the graphic icons for these aren't "real enough" elements that pan/zoom recognize. Fortunately most people won't encounter this because they'll be working with a template that has "stuff" in it!
This "condition" is also true for earlier releases but 2010 now has something that you might actually want to use Zoom to Fit to see even if other elements don't exist yet.
As you were...