Ironic thing about this is Zynga sees their relationship with Facebook as one of the weakness, as reported in their S1: "Facebook is the primary distribution,

Ironic thing about this is Zynga sees their relationship with Facebook as one of the weakness, as reported in their S1: "Facebook is the primary distribution, marketing, promotion and payment platform for our games. We generate substantially all of our revenue and players through the Facebook platform and expect to continue to do so for the foreseeable future, the filing explains...Any deterioration in our relationship with Facebook would harm our business and adversely affect the value of our Class A common stock." So Google+ could even benefit from working with Zynga, if they wanted to that is.