Facebook using Datalogix tracking

Datalogix has purchasing data from about 70m American households largely drawn from loyalty cards and programmes at more than 1,000 retailers, including grocers and drug stores. By matching email addresses or other identifying information associated with those cards against emails or information used to establish Facebook accounts, Datalogix can track whether people bought a product in a store after seeing an ad on Facebook.

http://edition.cnn.com/2012/09/23/business/facebook-datalogix/

Interesting.