I just got an email from a friend of mine, which might not seem particularly atypical, and this turned out to be hack-spam from his Yahoo account. What was jarring about seeing mail from him in my inbox is that he has been dead for six months.
IRL, we move people to cemeteries or other repositories of the dead and keep our interaction space for the living. On social networks and other digital interaction spaces, there’s no particular cost and some respect shown by leaving the presence of those that have passed as it was when they last touched it. But in time, all social networks will fill with the static presence of the passed on. It may be a little less cheerful to log in to facebook when your friend’s list is dominated by those who can no longer answer a poke.