“Care to write a status update to your friends? Facebook sets the default for those messages to be published to the entire internet through direct funnels to the net’s top search engines. You can use a dropdown field to restrict your publishing, but it’s seemingly too hard for Facebook to actually remember that’s what you do. (Google Buzz, for all the criticism it has taken, remembers your setting from your last post and uses that as the new default.)
Now, say you you write a public update, saying, “My boss had a crazy great idea for a new product!” Now, you might not know it, but there is a Facebook page for “My Crazy Boss” and because your post had all the right words, your post now shows up on that page. Include the words “FBI” or “CIA,” and you show up on the FBI or CIA page.
Then there’s the new Facebook “Like” button littering the internet. It’s a great idea, in theory — but it’s completely tied to your Facebook account, and you have no control over how it is used. (No, you can’t like something and not have it be totally public.)”