Sourdough,
Ole buddy, you are a little behind the times. Scientists have already succeeded in growing entire new organs for people. They don't use cloning. They extract stem cells from the patient's own bone marrow, cultivate it, mix it with healthy cells of his damaged organ, and like magic a totally new organ is grown. This has already been done with a pancreas, and I believe a kidney as well. The organ is not rejected, because it is the patient's own tissue.
Problem is, this procedure costs about $250,000! Too expensive for it to be practical.
As for the Mammoth, they are about 99.9% identical genetically to African elephants. We humans killed them off. So, cloning and releasing would be a wonderful way to right this wrong. And in all seriousness, think of the economic boom to places like Siberia and the Alaskan tundra country, if there were herds of wild mammoth roaming there, to be hunted for license fees.
Best, Mannyrock