Would should they be spending their money on? I would look at is as user acquisition to, Zynga will quickly have their box in the app cross promoting their other apps.
Nah, I don't buy that. Most users play games on a one-off basis. That is, people realize a game is fun, get a few of their friends to play with them, and they're off.
I don't think Zynga gains any long-term competitive advantage from this. Most people don't play games because they know the company that produces them, they play them because they are a fun novelty. Games are necessarily one-off successes at the mobile/social level, because there is not really a storyline or steep learning curve, so I believe that a company that produces one successful game is no more likely to produce another than a company with no previous successes, assuming equivalent technical know-how.