Nothing sneaky going on here with Facebook but they are making money from what you do in ways you wouldn’t guess unless you read, the Facebook blog on its policy which probably none of the billion users read. To put it simply Facebook monitors what you do and how you do it so that it can sell ads based on what you like and so on and so forth.
Now, this is actually a good thing, because you are most likely to see ads that you will like and interact with, which is also good for Facebook because more people will click on advertising.
Anyway Gizmodo sums up what this Facebook post means in plain english. And if you are one of those people who say their leaving Facebook because they don’t want Facebook making money from activities and data then fine… leave- you will be back and any other social network you go sign-up to will be doing the exact same thing with your data because they need to sell ads.