More interesting than the article itself was a short lecture on the grey goo theory that was buried in the comments. I have taken the liberty of reproducing it here for your reading pleasure:
Every time I hear the “grey goo” debate I ponder why some people love so much to hypothesize about the potential future without taking as much at a single glimpse at the past and present. The grey goo hypothesis states that, as a result of some technological advancement, there will be a matter that is able to function and replicate by consuming available background resources until all resources are consumed and turned into more grey goo. This position utterly fails to realize that there already is matter that does exactly that. It’s called life.
Life already functions in the most optimal way possible at consuming energy and replicating more of its own kind. But the “grey goo” scenario doesn’t happen due to a simple natural law of diminishing returns — as more and more grey goo (or, in our case, life) is produced, the less and less marginal advantage is there at producing more of the same kind. Identical species (or in simpler cases, where there are no “individual specimens”, identical biomasses (e.g. mold, grass) first spreads out by consuming the most readily available resource, but as its numbers grow and resources dwindle, it gains less and less marginal advantage at consuming more resources, and becomes its own competitor more than a co-operator. The fact that during the billions of years that life existed on Earth, Earth has not turned into a uniform mass of a single biomatter, utterly destroys the “grey goo” hypothesis.
On top of that, there is this “adaptability” thing. As grey goo spreads more and more, and becomes its own competitor, some strains of grey goo (lets call it blue goo), through trial and error, will function better when instead of cooperating with other grey goo, exploits it, for example by consuming grey goo directly rather than consuming what the grey goo consumes. In turn, the grey goo will now have to modify its behavior to not only consume and replicate but also to defend itself against blue goo. Then we get yellow goo which likewise will consume blue goo. Then we get some violet goo which adapts to the blue-yellow goo rivalry by, for example, becoming poisonous go yellow goo to consume while offering habitat protection to blue goo in exchange for some released energy from what the blue goo consumed.
This sequence goes on and on, until we get an ultimate form (brown goo) that sufficiently adapts to consciously exploit other forms of goo for its own needs, build constructed habitats for itself, wage wars on its own kind, and occasionally debate on whether all brown goo specimens originally evolved from humble grey goo, or whether they were created by some Divine Heavenly Goo instead.