All it takes is standing alongside a road or in a park next to a long lens to draw shouts of "what are you shooting, the moon?" But as any wildlife photographer knows a telephoto isn't used just to photograph objects that are far away...Instead it is most often used to draw the viewer into a scene--making it more intimate than it would be otherwise. This Alaskan Brown ("Grizzly") Bear was racing back and forth in a creek mouth looking for fish getting swept out by the tide. One of her runs brought her towards us. By using a 400mm lens (the unique Nikon 200-400mm f/4) and a Nikon 1.7x Teleconverter I was able to draw the viewer into the presence of the bear and almost make it look like she was running right at us--all from a very safe distance.
The keys to using a telephoto in this situation are to make sure you are focused on the eyes--as telephoto lenses have much less depth of focus than wide angle lenses--and that you have enough shutter speed to render the scene sharp (if you're going for an artistic blur then of course you need to tinker with it). A good tripod and gimballed head like the Wimberly Sidekick I was using really helps.