In a major breakthrough, Harvard scientists have been able to reprogram adult pancreatic stem cells into beta cells capable of producing insulin, simply by flipping three genetic switches.  That is cool enough in itself, but the real kicker is that they did this in vivo.  

Last year it was shown that an adult stem cell could be reverted back to an embryonic-like state (induced pluripontent stem cells).  But this process is one that takes place in vitro.  Not only do the stem cells need to be removed from the body, but then they need to be reverted to an embryonic state, then coaxed into differentiating into the desired cell type, and finally be placed back in the body for therapeutic purposes.  The Harvard team skipped all but the third step.  They have shown that adult stem cells can be transformed into other types of cells without being removed from the body, and without having to be retovertered into embryonic form.  Not only does this make for a less invasive procedure, but it would also avoid the current problem facing embryonic and embryonic-like stem cells: tumor formation.  

While this is definitely a big breakthrough, only time will tell whether it can be safely used in humans, and how many conditions can be treated with this procedure.  One thing seems certain, however: this is just one more nail in the coffin for embryonic stem cell research.  It is becoming both impractical, and irrelevant.