James Pethokoukis thinks it's curious that the 21st-Century Nanotech Research and Development Act explicitly omits funding for the study of nanobots, possibly because of a fear that tiny self-replicating machines might reproduce uncontrollably and eventually cover the earth (the so-called "grey goo" theory), and that the government's policy seems to be that nanobots could only be used for destructive purposes. 

[Via Instapundit]