A long-standing controversy in the world of nanotechnology is whether or not molecular manufacturing - the highly parallelized use of nanoscale robotic arms to manufacture human-scale products - is feasible. The molecular manufacturing vision, sometimes called "molecular nanotechnology" to distinguish it from nanotechnology in general - was first articulated by Eric Drexler in his landmark book, Engines of Creation, and later elaborated on in Nanosystems. But many scientists are skeptical it can be done. For what is possibly the most detailed debate on the topic currently available in text form, see this blog post at Soft Machines. If you're unfamiliar with Eric Drexler's original vision for nanotechnology, you should definitely order Engines of Creation.