An updated version of Engines of Creation is online
The Center for Responsible Nanotechnology (CRN), has an article that points out that the term "molecular nanotechnology" has been associated almost invariably with fantastic notions
like bloodstream nanobots, true universal assemblers (“meat machines”), and theoretically ubiquitous “utility fog.” Such concepts admittedly are fascinating to consider and someday may become reality, but they seem to be further in the future than are the middle-period developments that concern CRN.
I believe those who think of those things as fantastic notions are not aware of developments using current technology that are bringing them about.
From New Scientist, diodes could power bloodstream microbots
A new form of propulsion that could allow microrobots to explore human bodies has been discovered. Velev's diodes are millimetre-sized but any robot designed to work within the human body would have to be an order of magnitude smaller. In the past, attempts to shrink propulsive mechanisms have run up against a fundamental barrier in fluid dynamics: fluids become progressively more viscous on smaller scales. "It's like moving through honey," says Velev. But extrapolations of the team's measurements indicate the propulsive force will work just as well at smaller scales. "The propulsive force scales in exactly the same way as the drag. That's quite significant," says McKinley.
The first surgical microbot could be ready by 2009
A capsule insertable robot has been made in Japan
Nanoparticles have been used as drug delivery systems. They are more crude than the nanobot vision but they can be remotely guided to the tumor and then triggered from the outside to release material. So they are simple machines.
Similarly mini-bacteria cells are performing similar functions
Cellular repair is becoming possible as well. Magnetically assembled nanotube tips are being added to devices that can inject or remove organelles from cells
These things are not as capable as the Chromallocyte recently designed by Robert Freitas but it shows that such things are clearly not fanciful.
Meat Factories can be made using stem cells. There is existing work with test tube meat.
Step towards utility fog are being made by Intel with work on claytronics
Current claytronics components which are planned to be shrunk to about one millimeter
Projecting rapid manufacturing capabilities from current rapid prototyping, rapid manufacturing and fabbing could be not that far from the Engines of creation view of universal assemblers.
Combining the ovonic quantum control device with PRAM and other polymer components could enable more fabbable all flat (reel to reel) printing of computers and solar power cells.
Lasers, combined with metamaterials, nanoparticles and superlens could enable additive rapid manufacturing with 2 nanometer precision.
Non-molecular nanotechnology (microelectronics), pre-molecular nanotechnology (nanoparticles, nanomaterials), DNA nanotechnology, synthetic biology, graphene, fullerene nanotechnology, advanced chemistry, robotics, rapid manufacturing are making possible what was believed would require molecular nanotechnology. When full-blown diamondoid arrives what will actually be possible will be confounding to those who have not been paying attention or who are in denial.
We only will need molecular nanotechnology because we are not being creative enough with what we can already do or on the way to doing very soon. If we were not flushing money on the Shuttle and the Iraq War we could have mastery of space. If we were not confused about nuclear power we could have clean energy.