Facebook owns you

Kurt Opsahl, writing for the Electronic Frontiers Foundation, has constructed a timeline of Facebook's privacy policies. He's mapped out the shifts from 2005 to April 2010. He begins with:

Since its incorporation just over five years ago (Vic: can it only be that long?), Facebook has undergone a remarkable transformation. When it started, it was a private space for communication with a group of your choice. Soon, it transformed into a platform where much fo your information is public by default. Today, it has become a platform where you have no choice but to make certain information public, and this public information may be shared by Facebook with its partner websites and used to target ads.

Read "Facebook's Eroding Privacy Policy: A timeline" here. If you're yet feeling slightly meh about what happens to your data when you join Facebook you should read Ryan Singel's Wired article "Facebook's gone rogue" which gives you a more detailed overview of what happens to your profile information.

If any of this alarms you, then go here and read how to opt out of the bits you still can.

For an alternate view, read this. Daniel Castro has a point, "Facebook is neither a right nor a necessity". If don't like it, don't use it.