So, 10 million people signing up to give them free marketing data. Fun.
And they admit to using "web beacons" - aka 1x1 pixel clear .GIF images whose only purpose is to report to them and 3rd parties whenever it gets served up. And they also use them in email correspondance with their users for marketing purposes.
"In addition, we may also use clear gifs in HTML-based emails sent to our users to track which emails are opened by recipients. The information is used to enable more accurate reporting, improve the effectiveness of our marketing."