Wired is running an article by Ryan Singel about a privacy breech at Netflix and the resulting lawsuit: Doe v. Netflix. At issue is Netflix's intentional release of supposedly anonymous subscriber data to the public for a movie recommendations improvement contest. Concerned parties, however, are worried the data could be easily used to identify specific people by cross-referencing the data with other sources.
The primary concern is one's movie-watching habits and preferences could provide tremendously strong hints about one's sexual interests, religious beliefs, political affiliations, etc. For example, if you have rented Brokeback Mountain, Milk, and The Adventures of Priscilla, Queen of the Desert from Netflix, this data could potentially be used to indicate you have homosexual interests (whether you do or not). Perhaps you rented Lolita, The Lover, and Pretty Baby from Netflix. A nosey person might conclude you have an interest in underage girls. Maybe you rented movies about Ted Bundy, John Wayne Gacy, David Berkowitz, etc. from Netflix. You might be identified as a person obsessed with serial killers. Perhaps you rented movies about Che Guevara, Chairman Mao, and Joseph Stalin from Netflix. You could be viewed as a person with Communist sympathies. The examples could go on and on.
Your movie-watching habits and preferences say a lot about you. What they say could be inaccurate, but they do say things. In the hands of a malicious person, your viewing data can be used to reveal all sorts of information about you. Whether these revelations are true or not, the information could be used to embarrass, harass, persecute, or investigate you.
If you are concerned that Netflix has compromised your privacy by releasing your personal movie-watching habits and preferences, consider contacting an attorney. At the very least, contact Netflix to find out what they are doing with your personal information. Make sure Netflix responds to you in writing. It is your information. You have a right to know. You have a right to hold Netflix accountable for this careless behavior.