Paul: I would take it as a given that someday someone WILL create a gray-goo nanite and unleash it. This is not a reason to scream that the sky is falling, but is a reason to start planning out rational strategies to be prepared for it to shut it down when and where it occurs.

The Luddite's approach of "just stop ALL nanotech development EVERYWHERE!" is simply not in line with reality. It's coming. Start dealing with it. Sticking your fingers in your ears and shouting "LA-LA-LA! I CAN'T HEAR YOU!" is not a viable approach. The real question is "HOW will we deal with this WHEN it gets here?" not "How do we stop all this icky technology stuff from being built by those science-type guys?"

Another problem with the-sky-is-falling crowd is that they just don't take into account environmental and energy factors. Not all environments will be friendly to nanites and they have to get the energy to "eat everything in sight" from SOMEWHERE.