What is relevant is Facebook. Zynga's stock grew rapidly once Facebook's S-1 filings revealed that Facebook derives 12% of it's revenue from Zynga. This news cause a flurry of interest in Zynga, but the excitement has since waned, and both Facebook and Zynga have been scrutinized heavily since. This is to be expected, but I also expect that both company's stocks will perform well after May 18 and into next quarter.
Last, and possibly most important, is the misconception about how easy it is to launch a profitable mobile app to millions of users. Zynga now hosts about 80% of their games on their private cloud (the zCloud). This infrastructure separates Zynga from a group of 15 hackers who want to make the next Angry Birds. Zynga releases games in dozens of foreign languages; they have games on every social network and in dozens of countries, as well as in many emerging markets. The point is, it's easy to take pot-shots at Zynga's business model and claim it's a house of cards, but I think the reality is that Zynga is a well established company, with far vaster resources than many of their competitors. Mobile and social games are a clear-cut example of economies of scale.