IssueTracker

not sure if this is a bug or the intended behaviour
this is a way to get the new bounds


  zoomChangeListener = google.maps.event.addListener(map,'zoom_changed',function (event) {
    zoomChangeBoundsListener = google.maps.event.addListener(map,'bounds_changed',function (event) {  
      console.log(map.get_bounds());
      google.maps.event.removeListener(zoomChangeBoundsListener);
    });
  });

Not sure- I'll discuss with team.

Quoted from http://code.google.com/apis/maps/documentation/v3/events.html :

Note:  If you are trying to detect a change in the viewport, be sure to use the
specific bounds_changed event rather than constituent zoom_changed and center_changed
events. Because the Maps API fires these latter events independently, getBounds() may
not report useful results until after the viewport has authoritatively changed. If
you wish to getBounds() after such an event, be sure to listen to the bounds_changed
event instead.

It seems like this is the intended behaviour  (at least in  API V3)