Absolutly! we would never get these shots with out these optics. Furthermore, the VR or IS lenses allow for pretty decent sharpness at maximum tele without a tripod. In my case it is a must since I would not carry a tripod as I ski in the back country and see fleeting scenes of animals, by the time I set up a tripod they would be long gone.
In the squirrel pic I actually got to within a foot of the little beastie. He didn't seem to care very much... Thats why its somewhat high on the saturation... the flash wasn't far away.
Taken at the Mary Arden House in Stratford-upon-Avon, when my mother and I visited England this past August. There's a bird-of-prey center located there, and they fly birds for visitors.
Despite what I titled the post, Angus the owl wasn't really angry; he was nicely behaved. He just *looks* hacked off. Link gone