Nikon's Nano Crystal Coat technology is used in various professional-level lenses to reduce ghosting and flaring. It's a delicate 3-dimensional coating that incorporates not only nano-particles, but the air-spaces between them to create a delicate surface with an extremely low refractive index. Normal glass reflects between 8-18% of the light that it encounters, but the "N" coating has a transmission efficiency of over 99.9%. Naturally, such an ephemeral construct would be easily damaged by careless cleaning... let alone any cleaning. So is it safe to wipe a cleaning cloth across that AF-S NIKKOR 24-70 F2.8G ED?
Short answer: Yes
The longer answer is also very short. There is a simple reason why you can't inadvertently damage the Nano Crystal coat on your dearly expensive lens...
... the coating isn't on the outside surface of the front element. In fact, it's hardly used at all on any of the surfaces of the internal elements, only a few critical ones at best. Here is Nikon's diagram for the AF-S Micro NIKKOR 60mm f/2.8GED:
Yes, the Nano coating is only used one one lens element surface. In other words, just like the aspherical lens elements, the Nano coated components, being more expensive items to manufacture, are limited in number to the area of the lens design that will have the most impact.
Of course, harsh cleaning of any glass surface will run the risk of damaging coatings of any type, but if you read carefully, the word "damage" usually is prefaced by the word "may". Bob Atkins, for Adorama:
Myth: It's more difficult to clean dirt from multi-coated lenses and filters than un-coated or mono-coated versions.
Fact: Oil and grease are much more visible on multicoated optics, so it's more difficult to remove every last visible trace. For example, a grease smear (possibly left over from a fingerprint) which shows up on a multi-coated filter would be invisible on an un-coated filter. There would be the same amount of contamination on both. The oil is more visible on the multi-coated filter because it negates the anti-reflection effect of the coating and so appears as a brighter spot. On an un-coated filter the surface reflectivity is essentially unaffected, so it's much harder to see.
To put it into perspective, everybody should read this Roger Cicala post (Lens Rentals) to see how damage to the front element need not be completely catastrophic to image quality.