Facebook announced some great changes yesterday - users finally have a way to download all their information and photos, there's a dashboard to handle applications and privacy settings, and even a nifty new way to handle all of your social connections in their numerous and varied stratifications. It did, however, forget its much-needed mantra - opt-in, not opt-out.

If your friends have caught wind of the groups feature already, then hang on to your inbox, because things are about to get messy unless you tweak some settings...and fast.

Already, Facebook users are waking up this morning and complaining about the notifications they're receiving by email for groups they didn't agree to join. Expert Labs founder Anil Dash tweets "Oh, Facebook. I wanted to like groups, but now I'm on 50 unwanted email lists. More incompetent defaults, or an attempt to undermine email?" Video blogger Steve Garfield asks that Facebook "By default, never notify me via EMAIL of messages from groups that people add me to." The Huffington Post has a full slideshow of people complaining/moaning/groaning about Facebook.

Jason Calcanis sent an email to Facebook early this morning, because just after the new Facebook Groups feature went live, someone added both him and Michael Arrington to the newly-formed NAMBLA group. (NAMBLA, for those of you who don't watch enough South Park, is the "North American Man/Boy Love Association".) So not only were they both enrolled by someone else into a group they don't want to be a member of (we assume) but now they're receiving email notifications for everything that happens in that group. Thankfully, your group memberships are not shown on your profile page, so it's not as if they are suddenly publicly broadcast as NAMBLA members to anyone else...outside of existing NAMBLA members.

Edit: Your addition to groups does, however, show up in your friends' timelines, as pointed out by a commenter below. It just doesn't show up as a neatly organized list on your profile or as an update on your wall.

So here's the big thing about opt-out email notifications - while it's merely a simple, four-step process to opt out of email notifications for groups, you'll have to do it every time you join a new group and every time someone else adds you to a group. Not only do you not have the choice to join the group, but the second you're added, you're going to get email notifications until you repeat that four-step opt-out process yet again.

This isn't to say we aren't slightly (read: totally) in love with the new groups feature, but this particular part is going to drive us slightly (read: completely) bonkers.

Say it with us, Facebook - opt-in, not opt-out.