Snip from a Technology Review article:
Researchers at Carnegie Mellon University and the University of Pittsburgh have successfully directed adult stem cells from mice to develop into bone and muscle cells with the aid of a custom-designed ink-jet printer. They say it's a first step toward better understanding tissue regeneration, which may one day lead to therapies for repairing damaged tissues, as occurs in osteoarthritis.
Link to Technology Review article.
Jamais Cascio writes about it here (image grabbed from his site), and there's more over at Bruce Sterling's blog ("You might well call it the Meatrix"): Link. (via beyond the beyond)