A Betterhumans article from earlier in the week notes a small step forward in the quest to understand and replicate lizard-like regeneration of organs. Researchers are currently attempting to convince adult stem cells, which are partially differentiated and unable to produce all tissue types, to reverse their lifecycle and become more like embryonic stem cells - able to produce any tissue type. It is thought that this or a similar mechanism enables some species of lizard to regenerate entire limbs. This research is in its infancy, however, and we have a long, long way to go by the looks of things. All the more reason for greater funding and public support for stem cell research!
Link: http://www.betterhumans.com/News/news.aspx?articleID=2004-05-20-3