Facebook Ads Across the Web Are Coming
It's only a matter of time, but Facebook is working on it
The data retention policy already stated that Facebook was able to serve "social" ads outside of the site itself, now it makes it even clearer that it can serve any ad it wants on whatever site it wants.
Anything you do on Facebook can be used for ads, all of your actions and anything you say. This depends on your privacy settings, Facebook is not going to out you for saying something to a few friends.
But your anonymized data, used for targeted ads is fair game. Facebook is hardly the only company that keeps track of you to serve you targeted ads. It's certainly the company with the largest and the most detailed cache of user data on the planet and it's going to use it to make money.