They don't, however, seem to mention their names anywhere. If Facebook knows the name of the author, they can threaten to ban them from Facebook if they don't take it down (about the only leverage they have to exploit).

However, to get a real name, they would need to get Google to reveal an IP address, and then the user's ISP to reveal account details - hardly a simple process.

Google isn't going to hand over the IP of the authors, so they would need to file a (probably baseless) lawsuit and try to subpoena the names - something Google is likely to fight since the software is in their interests too.