I have heard some concerns about piracy in connection with 3D printing files. Apparently the PirateBay now has a section just for that. If things are open source then more power to them. If things that people worked blood, sweat and tears for that can better humanity, they deserve to be fairly compensated.

Obviously this is an inherent disadvantage to 3D printing, but I think as 3D gains ground, this will be an issue of concern.