Here is a review of the use of VR in Nikkor lens hand-held, no VR, with a monopod, and with no VR mounted to a monopod.All shots are taken at 200mm.
It is rough but I think it gets the point across.
VR off and hand-held
1/5th of a sec.
1/25th of a sec.
1/60th of a sec.
VR on and hand-held
1/5th of a sec.
1/25th of a sec.
1/60th of a sec.
VR off and mounted to monopod.
1/5th of a sec.
1/25th of a sec.
1/60th of a sec.
VR on and mounted to monopod.
1/5th of a sec.
1/25th of a sec.
1/60th of a sec.

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Canon EOS 5D + 50mm f/1.8
http://flickr.com/photos/nathan_ward