Seriously? I thought that his body was simple regenerated from it's radioactive death and de-aged, then re-aged before they put his mind back into it. To say he was cloned would imply there was still a dead radioactive half Vulcan corpse on Genesis somewhere before it blew up.
Huh, I never thought of Post-III Spock as a clone before. I imagine that the process is the same as stem-cell cloning, where tissues and organs could be duplicated by an original cell from the original body.