As always, the debates concerning whether the future evolution of humankind will lead to an evolved biological species, or a cyborg-synthesis, or even to complete AI, are ongoing. Recent research is now trying to synthetise DNA within nanotechnology - and one experiment was to place rat neurons into a robot. There is a large body of people who call themselves the 'Transhumanists', and they take this issue very seriously. The way forward, they say, is definately within a mixture of human and machine parts to produce an organic, human-engineered species with vastly increased intelligence.
To read up on this debate, check out this recent Transhumanist article.