According to a recent Twitter blog post, the feature will be rolled out soon, and it allows you to sort the accounts you follow into groups — for me, my favorite tech bloggers, favorite comedians (Eugene Mirman, anyone?), and best friends. Lists you create are defaulted to public (though you can make them private), and you'll be able to subscribe to other users' lists — a great way to discover new users.
The blog post doesn't give a date, but they've already been testing the new feature with a small group of Twitter users, so hopefully we'll see its release in the next week or so! Do you think you'll use this feature? How will you divide the accounts you follow into lists?