I read a page about this kinda thing the other day. Jay Leno uses it to replace old parts from many of his old cars that can't really be reproduced. While some machine shops can re fabricate something, it won't always be perfect. With these printers and scanners, he pops a part in, makes a copy, and gets a mold made of the part to make out of metal. Pretty cool stuff.
My school had a 3D printer, but I never got to fiddle with it because I don't know any 3D programs. I really need to take some time and learn how to use ZBrush, maybe I'll go back and make myself a lil action figure