Facebook's pure HTML tracking system

this is real - Facebook can track you as you visit each site with a like button whether you click the like or not, and whether you are logged in or not (if they choose to set a cookie for anonymous users).

But its not new. Its just noticed since FB started migrating some certs this last week

They've been snagging your history as you move around 'likeable' pages since the start.

Private browsing sessions and deleting cookies will obviously zap this.