Here's a great video to watch: http://www.youtube.com/watch?v=EMhNapObKQk. It's only 30 seconds long, so have a go. ... OK, you're back?
Now go have a look at this detailed writeup of the story behind that video, and the hornet's nest of who-invented-what and how-do-you-control-an-idea debates that have arisen over the past few days.
I know very little about 3D printers; I've never seen one in person, just read about them. I found this background paper by Michael Weinberg to be very well-written and interesting, though:
It Will Be Awesome If They Don't Screw It Up: 3D Printing, Intellectual Property, and the Fight Over the Next Great Disruptive Technology
Cory Doctorow is also doing a great job of covering this story, over at the BoingBoing blog.