Before last week, almost no one on Facebook created Friend Lists. Why? Because there was no point. Besides being able to send bulk messages (as long as your Friend List was under 20 people in size), all you could do after creating your Friend Lists was, well, look at them.

Starting last week, however, Facebook elevated Friend Lists to central status within the Facebook user experience by making it the basis around which users can specifically limit access to certain information for certain friends. By enabling Friend List-based privacy, Facebook has taken a major step toward solving a very complex problem – accurately mimicking the way in which we all limit access to certain personal information to specific friends.

Like in the “real” world, on Facebook, Friend Lists are a very private concept. Whereas your Groups affiliations are very public, no one can ever see what Lists you’ve created or put your friends in. The primary purpose of Friend Lists is to help you organize the myriad of people you’ve connected with so that you can share more information with confidence.

Has Facebook made the problem of limiting access to certain info easy for everyone with this release? Of course not. Whenever adding more robust and granular control, it’s impossible to not also introduce more complexity and conceptual overhead for users.

But by making Friend Lists so prominent – they’re now on every Facebook friend request and confirmation page – Facebook has for the first time created a context for millions of users to begin the (perhaps arduous) task of grouping friends into sets with permissions that mirror those in real life (and certainly much more powerfully than “we hooked up” or the Limited Profile ever did).

Look for Friend Lists to slowly increase in prominence in both the Facebook and Platform experience over the coming months. As Facebook knows more about how you organize your friends, it will then be able to offer more robust ways to communicate with them.