Facebook CEO Mark Zuckerberg has taken some fierce criticism for compromising his users' privacy. Today he issued a clever response, taking the primordial tendency of humans to form groups and rolling it into his product as a feature.

At a press conference and in a blog post titled "Giving You More Control," Zuckerberg rolled out two big new features, both clearly designed to assuage criticism from Facebook users that the site doesn't offer users enough control over the privacy, makes privacy settings too hard to navigate and even cynically manipulates settings to advance its own interests.

One, a simple exporter, allows users to download "everything you've ever posted on Facebook and all your correspondences with friends," although it doesn't sound like the downloader will export your actual list of Facebook friends or their public contact information, a feature that would be crucial in allowing people to move to other social networks.

The other, bigger new feature is a new version of Facebook's groups functionality, one that lets people segregate their conversations more easily, keeping, say, relatives from seeing pictures meant for a wild group of friends, or church pals from seeing a political rant intended for like minded campaign volunteers. Where Facebook's old groups system was cumbersome to set up and bereft of functionality, the new one is designed to be used in an ad hoc and flexible manner. Groups can be "open," with membership and posts made public; "closed," with membership public but communications kept private; or "secret," with both membership and content walled off. Groups feature live group chat, a shared wal and an optional email list. Friends can easily be added with one mouse click (there seems to be no process of having to invite members or accept invitations).

Wrote Zuckerberg:

We approached this problem as primarily a social one. Rather than asking all of you to classify how you know all of your friends, or programming machines to guess which sets of people are likely cohorts, we're offering something that's as simple as inviting your best friends over for dinner.

Facebook's new groups have already been compared to real-world in-groups and clubs. "This is the high school cafeteria clique model of human interaction," wrote former Google social networking staffer Kevin Marks. CNET's Caroline McCarthy predicted they'd become a new hub for the social maneuvering and humiliations of junior high school.

That's exactly right, but not a knock. For all the privacy they've taken from users — and they've taken plenty — it's nice to see that Zuckerberg and his team have come up with at least one good way of helping users take some of it back. Facebook's new groups feature is fairly basic. In fact, at its essential core it's downright primitive, drawing on one of the most basic of human instincts. And that's exactly why it will be such an effective tool.

For more from the announcement, see Gizmodo's detailed coverage.

[Photo of Zuckerberg with two Facebook employees at today's announcement. Getty Images.]