Here's something immediately useful for those who can't be arsed reading the whole article:

> People can remove their information from MasterCard's analysis by providing their card number on the "Data Analytics Opt-Out" page at www.mastercard.us/privacy.

There are three different opt-outs available (roughly "stop tracking my browser", "stop tracking my email", and "stop tracking my card"), and apart from a CAPTCHA, it's really very frictionless to opt-out.

Now time to read into how exactly they define "opting out" and what that entails to me and my data.

EDIT: apparently, they're serving those opt-out forms via Akamai, so I get a lovely "SSL Error" page in Chrome when I hard type the "https". Cute.