Well, not exactly, but scientists at the University of Pennsylvania School of Medicine have shown that mice with skin wounds can regrow hair. Something about the healing process caused the cells in the healing wound to “open an embryonic window,” and do things that can normally only be done in an embryo, like making hair follicles. Stem cells were recruited to the area and formed new follicles, just as they are formed in the embryo.
Although this might eventually lead to a new cure for baldness (which would certainly please some), it also could lead to more medically important developments, like improved wound healing.
What is most intriguing, at least to me, is that this is the first time anyone has demonstrated actual tissue regeneration in mammals. Some animals, like salamanders, can regenerate an entire limb or a tail, but the only kind of regeneration shown to occur in mammals (up to now) requires some fragment of the original tissue.