To me, natural horsemanship simply means communicating to the horse in it's own langueage. When I lunge in the round pen, using Monty Roberts and John Lyons 'Round Pen Reaoning' I am talking to the horse with my body, my actions, in his own langueage. And every horse on the planet knows this langueage.
I use this training, only when I need to restablish dominance and to build a bond. For tying, saddleing, I guess I use more mechanical methods, and picking up feet. I believe if a horse tries to bite, give him a little slap to let him know it's wrong!
I don't think Natural Horsemanship could ever be a training program in itself. I also don't belive that "Natural Horsemanship" is, oh, if the horse kicks me, I'll hike my leg up and kick him back like in the wild. No, that's stupid, dumb, and could cause serious injury to you way more than it ever could the horse.
But on the basic level, I think it is the best way to etablish dominance, and a bond of trust with your horse. And, let me tell you, there is nothing more magical then having that horse follow you around the pen without a single use of mechanical equipment, only body languege. To have the horse stop when you stop, without even touching him in anyway. To turn when you turn. It's just amazing.
Lettin' the cat outta the bag is a whole lot easier than puttin' it back. -- Unkown