One interesting place that nano-tech will be is medicine. Consider gradually replacing human neurons with engineered replacements that don't wear out or die. When the process is complete, do you have a human brain analog that lasts (effectively) forever? Is imortality within our grasp? (except for the "Hey ya'll, watch this" crowd)
/john
Yes. Even before nanotechnology arrives gene therapy and DNA manipulation will be pushing the envelope towards immortality. People in the various related fields measure life expectancy by how many years are added to a persons expected life to the measure of time it takes to achieve the next life-extension breakthrough. That is, a new technique takes two year to develop that adds one year life extension. Eventually, and not that long, perhaps in the next ten years the rate of life extension progress will be be adding years quicker than we age.
For example, say life expectancy is 80 years and next year life expectancy is increased to 82 years via "X" technology. The person has passed beyond the point of every reaching an expected death-date so long as life extension technology continues advancing. So the following year the person is another year older but life-extension technology has pushed life expectancy to 85 years. The person lived one year and during that time gained three expected years of life.
A very important aspect of achieving immortality is being able to store a persons "I-ness" (sense of self-awareness) and all aspects of the mind off site (some sort of specialized database) so that if an accident kills the person not only can the body be brought back to life but the mind will be restored as well.