In the same vein as an earlier article on my blog, Giving Yourself Away With a Facebook Login, Alexis Madrigal writing in the atlantic in I’m Being Followed: How Google—and 104 Other Companies—Are Tracking Me on the Web quotes Joe Turow saying:

If a company can follow your behavior in the digital environment – an environment that potentially includes your mobile phone and television set – its claim that you are “anonymous” is meaningless. That is particularly true when firms intermittently add off-line information such as shopping patterns and the value of your house to their online data and then simply strip the name and address to make it “anonymous.” It matters little if your name is John Smith, Yesh Mispar, or 3211466. The persistence of information about you will lead firms to act based on what they know, share, and care about you, whether you know it is happening or not.

She refers to the WSJ investigation called the Web’s Cutting Edge, Anonymity in Name Only, also worth reading.