It seems that Facebook wants users to use its "smart lists" feature a little more. Inside Facebook is reporting that some Facebook users are now seeing suggestions for people to add to their "close friends" list, right in their sidebar.
Facebook is also encouraging users to organize their lists after hiding a story on their news feed. After hiding a story, users will be prompted with a link to use the acquaintances list to curate their news feed. The link takes users to a page filled with suggestions on which of their Facebook friends they might want placed into the acquaintances list. Stories from friends in the acquaintances list will show up less often on a news feed. Also, when sharing content or posting an update, users can choose to share with "all but acquaintances." The close friends list works in a similar way, but shows posts from friends in the list more often and has an option to share only with close friends.
Facebook's smart lists were introduced last fall to compete with the newly launched Google+. Where Google+ required all social connections to operate through its "circles," Facebook did not start out with such a system, and use of its lists is not as widespread. By advertising the Google+-esque feature, Facebook is effectively encouraging users to clean up their clogged news feeds by segregating their friends list into two main categories.
(via Inside Facebook)