The first question to ask yourself is if you have gone into Facebook and verified the security settings on your account. On my other blog, TheSocialNetworker, I did a quick 2 minute video showing you the changes Facebook has implemented to the default settings on privacy settings.
You should be aware that their attempt is to make more of the information you have uploaded and continue to upload more public. Meaning such things as pictures, profile information and wall posts available to the public stream. You do have the ability to restrict this and should take the time to make the effort.
If you have been concerned with how much information is available about yourself online, this should raise that to new heights. For Facebook to take the stance that they can make sweeping changes to publicize what was personal has many people deleting their accounts.
I could have seen Facebook implementing a feature request where you have to log in and select what items you wish to be public, and I mean area by area. Not in large category scale. Some would claim that would be a time consuming process and overhead they did not want to absorb. I counter with the fact that you have already established security guidelines and expectations that apparently can be changed on a whim based on what advertisers wish and your expected growth.
Facebook is trying to become the phone book of the Internet. Are you unlisted?