I forgot to add, one can use Google maps to find places like government buildings. churches, Wal-Mart, and about every resident living in Hollywood Hills to tag.
Also, if someone lists you, and then you are a victim of a robbery, due to being listed as a gun owner, you can sue the one who listed you, for the damage, along with the criminal who did it. Being a member of Google+ would make the lister easier to find. This is a good case of where the SCOTUS says there is a limit to the 1st Amendment.
Update: I just sent off a complaint to the Ohio Attorney General, asking for him to seek an injunction against the app, and Google, and then bring suit for any damages this may have caused. I urge anyone on here to do the same.