Over on his blog, Jon Radoff provides a terrific map of the history of social games. Really worth looking over in its more detailed version. He starts with ancient times and wends his way down to the present (leaving out many games, even some seminal ones, but still catching the main currents).
What I'm most interested in is where we are now and (of course) what's next. Jon's brief taxonomy separates current social games into Strategy, Sim, RPG, and "experiences" (music, pets, etc.). Not a bad set of categories -- and note that this includes some social games as descendants of MMOs and VWs as they descended from paper RPGs and MUDs. I'm particularly interested in the potentially convergent growth of RPGs (Mafia Wars, etc.) and Sim games (Farmtown, Social City), and whether both can interweave well with some kinds of strategy games. Are these kinds of games sufficiently social that as they evolve they can support hybrids and cross-overs, or are we more or less stuck with these genres?
(Crossposted in slightly edited form from my Online Alchemy blog.)