Zynga is hosting a press event at headquarters this morning.

Invitations for the event mention “a new play,” with an image of an airplane flying overhead. So we wonder whether the imagery hints about the developer’s next game release.

Zynga’s largest partner yesterday announced a new mobile platform and version of Facebook for the iPad, so that might factor into today’s announcements.

The company’s newest game, Adventure World, is the fastest-growing application on Facebook right now. It currently has 3,117,883 daily active users and 37,578,440 on a monthly basis; the latter tally has grown nearly 8 million over the past week.

Readers, what do you think Zynga might announce this morning?