Those that know me will know I have a thing for trans-humanism (or post humanism etc).
The basic concept is that the human body is scanned at the deepest level possible and the remains are simulated on a computer, in theory this recreates the human. Currently it is predicted that by 2020 computers will exist that have computing complexity to match the human brain (ie comparable numbers of connections). Quite when AI will be reached (if we do ever reach it) is a moot question but highly likely (unless something like the soul does in fact exist).
This article interestingly looks at what the economic, environmental and sustainability aspects of humans being uploaded to computers will be. The conclusion: its probably a good thing as the entire current population would probably be fitted into a 100x100km grid coated with solar panels.
Very interesting read, for more information Charlie Stross' 'Accelerando' is a very good fictional investigation of the singularity (what will happen if true AI is achieved) as well as post-biological humanity.