Paul Fidalgo (a good fellow - follow him on Twitter) blogs about virtual mouse brains:
Paul's question is important:
At what point is that virtual mouse no longer “virtual,” but sentient…sentient under the law?
If we believe that the mind is the activity of the brain, then there is no functional difference between a virtual brain and a biological brain. Because of this there are serious ethical concerns about attempts to simulate brain functions which result in awareness. There is no reason to believe that a reasonably detailed simulation of a pain signal isn't an actual pain signal, for a certain value of 'reasonably detailed'. We need to have discussions about this now, before we unwittingly create and possibly torture artificial consciousnesses.