Zynga: Rising star or falling comet?

I will start by personally stating the following. I do not currently like Zynga. I admire them, but I do not generally enjoy their games or appreciate their business model. They have published 15 different "social" games at this point, and with the exception of Words with Friends, their clone of scrabble, I do not like any of them. Zynga however is making quite a decent amount of money, unlike many other internet start ups that actually do useful things, such as Pandora, and that impreseses me.
Zynga has 227 million monthly users. In terms of comparison, WOW, or World Of Warcraft, has 10.3 million subscribers. However, these numbers should not be taken as the same thing. A WOW subscriber pays $15 a month in order to trapeze around Azeroth, while a Farmvillian might pay next to nothing. But now, things get interesting.
The method of distribution for getting money in WOW is fairly simple. You play WOW. You play Blizzard money. That money does nothing more then allowing you to play the game. You might pay some motivatedl kid in China to level your Blood Elf up, and collect a huge amount of gold, but this goes on outside of Blizzards system, and gold farming is its own story.
Within Farmville, you pay to get extra gasoline, extra flowers, extra gold, etc. You pay in order to get a leg up on the competition, who happen to be your friends. At the same time though, you want your friends to continue playing, and this is wear Zynga gets interesting.
Infectious Disease Modeling of Social Contagion in Networks is a paper published by a group from Harverd, based on a long term study. The paper demonstrates that obesity and smoking can both spread similar to virus’s in social chains. However, in the overview, it says something very interesting.

“Information, trends, behaviors and even health states may spread between contacts in a social network, similar to disease transmission.”

Facebook if nothing if not a social network. That's what it is. And it makes a perfect transmission vehicle for the Zynga virus. Or at least it did for quite a while. If you sent a notification to a friend to invite them to a game it would show up and they would see it. They might also see that all of their other friends are playing, and think “Why not?”. They would then play the game just to fit in. This led to the popularity, and the massive spread of the Zynga virus.
But a virus can’t spread by its self, and the game design of almost all their games led to the spread. Players needed a minimum level of friends playing the game in order to unlock further levels of items and land expansion. So players would send their friends invite after invite begging them to join the game.
And people joined. Oh, people joined. They flocked to their virtual farms and mob dens, and spent real money. But eventually, those who didn’t play got angry with the spam invitations and Facebook did something that it rarely does: Actually listened to its users. They redesigned the interface to stop the currant deludge of ads, and Zyngas game virus sufffered for it.

Curantly, Zynga has a pile of money, a huge number of game designers. It might making some more good games, and it might not, but only time will tell.