[psychotik]

Wait, how is this even technically possible?

Sure, Facebook can see sites you visit which use Facebook Connect in some form, but can they actually "create a running log of the web pages that each of its 800 million or so members has visited during the previous 90 days" like the article claims?

[raganwald]

They can certainly track visits to those sites displaying a Facebook “Like” button or other FB spoor.

[jamie_ca]

When your browser requests the like button from FB's servers, the request includes a session cookie, and the referer header indicating which page the like button was loaded from. Super easy to log, though it does generate a boat-load of data.