In a previous post I walked through some of the new features Facebook has launched for us third-party websites. In a nutshell, facebook users can share their friends' information. That means under normal privacy permissions, your friends can share your likes, your posts, your birthday, etc to third party sites. The example is the birthday card site, it needs to know all of a user's friends' birthdays in order to send them all cards on the right day.
When facebook launched "Places", I was curious, so I dugg in a big and sure enough, the same thing exists. Friends can share the check-in locations that their friends have posted. If you don't want this functionality, find this screen:
Go to "Account" -> "Privacy Settings"
At the bottom of the page is a section called "Applications and Websites" click "Edit Settings".
Next, find the section called "Info accessible through friends". This is the information you grant friends to share with third party sites. You might want some of these, like, you may not get a birthday card if you don't share your birthday. Choose wisely though, if you use "Places" and you check in to places you'd rather nor broadcast (why are you putting them on facebook anyways?) you should uncheck this box.
