Wait a minute, you mean gamers don't play mindless, time-consuming games if they aren't being inundated with reminders from their friends (social pressure) to play? NO SHIT!
I hate Zynga and their games almost as much as I hate seeing app spam all over Facebook. If not for Facebook's blatant efforts to undermine their users' attempts to maintain SOME level of privacy, this might make me think Facebook actually had their users' interests at heart.
[/cynicism]