Here are two examples of nanobots in fiction. Prey, by the late Michael Crichton, approaches them as miniature terminators with a hive type mind. Diamond Age, by Neal Stephenson, puts them in a more positive light, although nanobots become their own form of pollution. I like these two as they really look at the research and or results of nanotechnology. Most fiction doesn't really give an explanation for them and just uses them to make someone speak an alien language or heal overnight.
Whether science actually develops them or not, I see them sticking around in our collective imaginations for quite some time.