I just listened to an excellent NPR Morning Edition commentary by David Ropeik of the Harvard Center for Risk Analysis. He talks about use of the Precautionary Principle in formulating government policy on science, and asks the all-important question of when exactly enough proof exists that a product or technology is safe, and when are we being so safe that we're sorry and risk sacrificing the potential health benefits of genetically modified foods, among other technologies.
Those in time zones west of Michigan might still be able to catch the commentary on the air. If not, NPR usually posts sound clips from Morning Edition later in the day.
If you want to know what an idea as seemingly abstract as the Precautionary Principle might mean to you, or to the nanotech industry, take a look at this news out of Britain. If enough people believe a technology is harmful, why, then it must be true, right?