I'm sort of torn on my opinions of the whole cloning thing. On one hand, I can see the benefit of putting a great horse back into the gene pool that either had limited breeding or was never bred (think Charmayne James's Scamper).
On the other hand, if they start allowing registration of cloned horses or offspring of cloned horses (last I knew, any foal with a cloned parent wasn't eligible for registration either), then there will cease to be any progression in the bloodlines. I mean, instead of crossing on HBC and continuing to cross on his sons/grandsons with other lines to improve the breed, everyone would be wanting to cross on HBC himself and we might lose out on potential great horses that would come from a certain cross 4 or 5 generations down the line.
So much of the QH world is already traceable to this one certain horse or this other certain horse (how many QH in the world do you think have King or Wimpy in their bloodlines somewhere), having cloned horses just increases the potential for line-breeding...and opens up a whole new level of line breeding.
I don't know, I think I'm of a mind that they should just leave it well enough alone and, instead, continue the improvement of the breed through legitimate and responsible breeding practices.