And then there's Farmville, or Scamville, as Michael Arrington called it in 2009. He sketched out an entire ecosystem of empty gamification on Facebook, most of which is still happily chugging along as I write this - although this particular form seems possibly to have run its course with Zynga's troubles on the stock market. (But here's another article just this week describing Farmville as a game that has simply dispensed with gamification in favor of simply being a straight-up virus.)
The point of including all that is that Zynga is exploiting systems that come perilously close to ... well, society. And their social games do, in fact, act like biological and metaphorical viruses. They're a pure form of simple meme. The fact that they made Zynga boatloads of money is what drew my attention (along with the entire industry, giving rise to the term "gamification" in the first place), but the phenomenon is in itself interesting.