http://www.informationweek.com/news/showArticle.jhtml?articleID=195200003
Raymond Kurzweil, the person who pioneered optical character
recognition (OCR), text-to-speech synthesis, speech recognition
technology, and electronic keyboard instruments (from Wikipedia.),
and considered one of the most intelligent people in terms of
predicting future technology is saying 2-3 decades nano-technology
will be advanced enough to fix our bodies and play the roles of
some of our cells.
This guy isn't a joke either:
"Kurzweil isn't writing science fiction. In fact, Microsoft's Bill
Gates, a robotics director at Carnegie Mellon University, an MIT
professor, and a physicist have all endorsed his book. He has
received the National Medal of Technology and the Lemelson-MIT
prize."