The wisdom of dead people

One pitch a day: in August of 2011, I dedicate twenty minutes each day to writing an "elevator pitch" for a story or a game.

In the future, the social network gathers almost the total sum of human interactions. People show so much about themselves on so long a timeframe that computers become able to essentially mimic them. This function is useful on many levels and widely used. People get rewarded for building the product and the tool that their persona is.
As a result, dead people can still interact with living ones, or look like they can. They pass Turing's Test. Orphans express grief to parents, partners ask advice to dead associates, politicians flock to deceased leaders in hope of arbitration and guidance. Dead people's memories and opinions become an ever growing part of society. The persona have no solid legal status, but they still need to be convinced like normal human beings before giving out their knowledge and love.
Another stage results from the thirst for life extension. Processes are devised to assure that everybody gets a chance to live a very long time. When people die, cybernetic implants in the skull inject chemicals designed to preserve the brain. The connections to the network remain, the best to keep the brain active and to monitor its health. Dead people, assisted with their persona, are granted rights. Policies are put in place to protect their interests. The influence of people who passed away grows in the society.
At some point, dead people outnumber living people. They perform many functions with robotic bodies. The interests of the living are less and less of a concern.
In the end, to prevent them from pulling the plug, robotic death squads kill every human being still alive, making sure their brain is not damaged and greeting them into the community of the dead.