From a recent article in the NYTimes about the new Facebook Beacon program:
“Isn’t this community getting a little hypocritical?” said Chad Stoller, director of emerging platforms at Organic, a digital advertising agency. “Now, all of a sudden, they don’t want to share something?”
This guy is completely missing the point. There is a big difference between explicitly sharing information, which is what Facebook user's have been doing up to this point, versus the implicit sharing that the Beacon system is doing. I'm not a Facebook member so I can't comment on the opt-in or opt-out features the system which would make it more explicit and only slightly less disturbing.
MoveOn.org is running a petition that I encourage you to sign.