It is in the best interest of a social network to have everyone visible to the world all the time. So usually there are default privacy settings, which usually increase who can see you, rather than limit who sees you. Facebook has always had privacy default settings to a broader default (usually Friends or Friends of Friends) including your identifiers (name, city) that are part of common search to anyone. All other settings can be managed by the user, however, many users do not double-check their privacy settings.
With the latest change, Facebook info is now being communicated to the larger web, based on what pages and sites you visit and this info gets shared with your friends (like the games you play). By default, it is set to allow. In order to disallow, you need to go into your privacy settings and untick the “allow” box. A lot of work and digging for the casual user. There are glitches in the disallow, and because some people have still found their comments or choices showing up on the web, they have cancelled their accounts. (Some private chats apparently also became public through a glitch, but has since been repaired.)
Here’s my feeling — when you are writing something online, there is ALWAYS the risk that your word will show up somewhere you don’t want them to. Or that by googling your name, something about you will come up on someone else’s site, or in a picture, randomly (or intentionally) posted. That means that you MUST pay attention to what you say. Assume your private messages, could, by a software error, become public. Or that your scathing email may not be as confidential as you think. Or that your post might get hijacked and published by someone else under their name without giving you credit or asking for permission.
All this info is “cloud” info — it isn’t ours. What you write on Facebook, sits on Facebook servers. Not yours. Your Gmail sits on Google servers, not yours. Ditto for Twitter, your blog, Google buzz, classmates…and on and on and on. Just because we are used to it and use it, still doesn’t mean it is as private as you think.
If you enjoy Facebook, or use it for marketing your business, keep using it. Why not? Just always remember not to get lulled into a false sense of online security.