Although Facebook officials promise that they personal information they obtain is solely used to tailor advertisements to be specific for each user's interests and that they do not sell the information to theird parties, it is still not a fact openly shared with its users. Regardless of whether or not this should be deemed "unethical," should it at least be clearly stated and shared with users that Facebook does track you upon registration?
Many Facebook users take advantage of the privacy settings and assume that since they take precaution in what gets posted to their friends and who can find them when being searched that they're privacy is being highly protected. However, would they have the same feelings toward Facebook if they knew that the website has been tracking and following them after they exit the web page? Despite personal opinions, Facebook has not openly shared their user's information with any other companies as far as public knowledge goes, and promises never to do so.
The article referenced can be found here: http://abcnews.go.com/Technology/facebook-tracking-scrutiny/story?id=14960711