In addition to tagging photos, Facebookers can now tag friends in their status updates and soon even within applications. All it requires is adding the "@" sign in front of the friend's name.
The "@" will not show up in the posting (so if you're the friend, you likely won't realize this).
Some people have their profiles open to the public. Most do not. This makes it wide open for anyone, regardless of their personal settings, to be fair game on the Internet every time they are mentioned in a status update or application by someone with more permissive permissions.
This is an advertiser's dream that will exponentially increase page views. For Facebook it is a way to get more content out from behind private user walls and higher up the page rankings in search engines.
Is there going to come a time when it will be virtually impossible to keep your Facebook life private within your own circle of friends?