This project at Washington State University is incredibly nifty. Researchers use a 3-D printer to make a bone-like material that can temporarily do the job of bone, while serving as a scaffold for new bone to grow on. Over time, it dissolves safely.
Read more about it on the WSU website
Source: http://boingboing.net/2011/12/02/3-d-printer-makes-scaffolding.html?utm_source=feedburner