Emil Protalinski for ZDNet:

“Facebook does not track users across the web,” a Facebook spokesperson said in a statement. “Instead, we use cookies on social plugins to personalize content (e.g. Show you what your friends liked), to help maintain and improve what we do (e.g. Measure click-through rate), or for safety and security (e.g. Keeping underage kids from trying to signup with a different age). No information we receive when you see a social plugins is used to target ads, we delete or anonymize this information within 90 days, and we never sell your information.

Nik Cubrilovic claimed last week that Facebook was tracking its users even after they log out of the social networking service.