Thom's recommendations on when, and when not to use Vibration Reduction (image stabilization for Canon folks) are consistent with my own, with one exception. Thom recommends against using VR when you are using a Wimberly type gimbal head that isn't tightened down. My experience with long lenses with a Wimberly (gimbal) head is that VR can help, as long as your shutter speed is less than 1/500th.
Thom's article should be required reading for every photographer that habitually uses VR (IS) as a matter of course:
http://bythom.com/nikon-vr.htmKeith