The industry perception is that Mark basically thinks of FarmVille as an extremely effective spamming machine, not a game people actually enjoy playing... Problem for Mark is that he knows Facebook games are the easiest way for Facebook to get people to start using Facebook Credits – a product he actually does believe in. (The comparison is that people started using PayPal because they were already using eBay.)"
That might explain the purported tension between FarmVille creator Zynga and Facebook, even though the source for this bit of news is "industry perception," whatever that means.
[Business Insider via SFGate]