Facebook also revels in unintentional irony:
Facebook is about sharing information with others
We allow you to choose the information you provide to friends and networks through Facebook.
These statements create the lines you need to read between. They do not specify whether you have an opt out or an opt in policy, but that's not even the point. The point is, whether you opt in or opt out, Facebook still collects your data. Whether or not they show it onscreen or not is only marginally relevant. They have records of how you have used their site, and that information is valuable to people who want to sell you things.