Stem cell research has demonstrated enormous potential for both scientific learning and novel therapeutics. As described, clinical applications are underway for many of the biological systems. There are some diseases such as leukemia in which stem cell therapy has already become routine, conditions such skin transplantation for burn victims where stem cell trials are underway, and still others diseases like inflammatory bowel disease where stem cell therapies are very early in development. There are technical challenges at nearly every step of stem cell therapeutics: stem cell acquisition, manipulation, prevention of tumorigenesis, purification, transplantation and prevention of rejection. Progress is slowed by the further hurdles of financial, ethical, cultural and political concerns. Nevertheless, the rate of advancement has become asymptotic from the early days of detecting teratocarcinomas in mice. The mechanisms of stem cells are slowly being unraveled, from gross concepts such as niches and cell fusion, on down to individual cell signaling factors. Combined with novel approaches in molecular genetics and bioengineering, the possibilities for stem cells are very much infinite.