As part of the new Facebook features launched last week, users now have the ability to create and/or join groups of friends. The idea is that you don’t necessarily want to share the same information with grade school friends as you do with your book club. Fair enough. But as sometimes happens with Facebook, it’s the privacy issue you have to watch out for.

See, you can’t elect to NOT be eligible for these groups. If you’re on Facebook, you can be added to a group. Someone else can add you to a group without your knowledge or permission and then it’s up to you to go back in and withdraw from that listing if you’d rather not be associated with them.

Soon after this service launched, Facebook founder and CEO Mark Zuckerberg found himself added to a group called NAMBLA, an organization that supports pedophilia. It was a prank, done by one of his Facebook friends, but it was done to point out that these groups are “opt out” rather than “opt in”.

Facebook has since made statements that they don’t think this will be a big problem and if someone is being a jerk, maybe they should be unfriended and lose the power to prank. But Facebook isn’t planning on changing the way these groups are arranged. Essentially, they’re relying on Facebook society to behave like regular society: you CAN be a jerk, you CAN say horrible things about people, but you shouldn’t and most people don’t.

We talk with Wired staff writer and frequent Facebook critic Ryan Singel. He thinks this idea of great power / great responsibility will be a good thing for Facebook users. We also check in with Judith Donath, faculty fellow at Harvard’s Berkman Center for Internet and Society, about how Facebook is designed around getting you just interested enough in other people’s private lives to get you to push the boundaries of how much you’ll share about yourself.

Also in this show, we check in with our app reviewer Susan Orlean (she’s a New Yorker staff writer and best-selling author in her spare time) about some of her favorite to-do list apps.