Joshua Porter breaks down social design into three eras, and suggests a fourth stage – where we find ourselves today:
Additionally, much of the current evolution of social software is in improving the communication between people who provide a service and people who use a service. This is what I think is meant by “social media marketing”. This is somewhat of the fourth wave…when social applications not only improve the conversations between people using the site, but between people who provide the site and those who use it. (Tearing down the firewall isn’t easy) While email has done much of the heavy lifting here for many years, the mere act of putting these conversations public changes further interaction around them, while scaring the wits out of executives who worry that negative conversation will bring down their empire. (What they don’t count on are the fans they have who defend them)
So while all of this stuff is constantly evolving, and the word “social” is bandied about in countless ways, social design is relatively concrete: it’s designing software that support social interaction.