I never understood this thing with Nikon and motors in the body - why is that?
Nikon cameras and lenses used to autofocus by having an AF motor in the body which would drive the lens to AF. When they started bringing out smaller, more budget consumer DSLRs, it was when they had started moving to lenses with the
AF-S designation, lenses which had their own inbuilt focus motors (like Canon). Although this is purely speculation, it's likely to be because it allowed the latest lenses to have the latest in focus motor technology, in the same way that Canikon having VR/IS on the lens rather than the body means that the lens would always have the latest iteration of the technology, rather than being limited to what your camera body left the factory with.
Because of the increased number of smaller DSLRs, they began dropping the focus motor - the vast majority of people who would and did buy the entry level cameras were rarely likely to look past the kit lens and maybe the 55-200 VR budget telephoto (which was also AF-S). As a result, Nikon's product range can be sectioned off into those which do have AF motors (the higher end cameras) and those that don't (D3100, D5000, D5100, D40, D60 etc.). The reason why it matters is because before AF-S lenses, the autofocusing lenses (AF/AF-D) required the camera body focus motor, so obviously if you mount one of those older lenses on a camera with no focus motor, you'd have to manual focus.
For most people, it's not a make or break thing. Comments like the one above this seem a bit silly, as 10 seconds on Google or a forum like TP would rectify any possible concerns on compatibility - in this day and age of constant internet exposure, only a silly person doesn't do the research.
/boringeveryonetodeath