Google's driver-less cars and robot morality

In the New Yorker, an essay by Gary Marcus on the ethical and legal implications of Google's driver-less cars which argues that these automated vehicles "usher in the era in which it will no longer be optional for machines to have ethical systems."

Marcus writes,

Your car is speeding along a bridge at fifty miles per hour when errant school bus carrying forty innocent children crosses its path. Should your car swerve, possibly risking the life of its owner (you), in order to save the children, or keep going, putting all forty kids at risk? If the decision must be made in milliseconds, the computer will have to make the call.