“Facebook does not track users across the web,” – A Facebook spokesperson on September 25, 2011

and

“Generally, unlike other major Internet companies, we have no interest in tracking people.” – Facebook employee on September 25, 2011

v.

“A method is described for tracking information about the activities of users of a social networking system while on another domain.” – Facebook Patent application dated September 22, 2011

Whoops

See: HowTo: Setup secure and private Facebook browsing