"It took us too long after people started contacting us to change [the Beacon ad program] so that users had to explicitly approve what they wanted to share," Zuckerberg conceded. "Instead of acting quickly, we took too long to decide on the right solution. I'm not proud of the way we've handled this situation and I know we can do better."

Kathryn Montgomery, professor of communication at American University and author of "Generation Digital," said in a telephone interview that the Beacon issue, which Facebook hopes will go away after issuing "the most minimal mea culpa," is merely "the most visible part of what is a really massive system of data collection, and a few minor changes won't make much difference."

Turning Off the Facebook Beacon

User concerns about Beacon, which gathers information about some transactions with third-party companies and incorporates that information into Facebook's News Feed (which in turn is visible to a user's list of friends), have been steadily growing.

From the start, some users were upset about the fact that Beacon was initially set up as an "opt-out" program, which meant that users had to choose to block the broadcast of third-party activity on a case-by-case basis. Many people either forgot or didn't catch the quickly disappearing pop-up with the opt-out option.

Facebook community outrage boiled over, however, after several well-publicized incidents in which holiday surprises were ruined when shoppers failed to opt out. Facebook initially changed the ad program to make it opt-in and then announced that users would be given the option of turning off their participation in the Beacon program altogether.

"We were excited about Beacon because we believe a lot of information people want to share isn't on Facebook," Zuckerberg said, "and if we found the right balance, Beacon would give people an easy and controlled way to share more of that information with their friends. But we missed the right balance."

Information Still Flowing to Facebook

"People need to understand," Montgomery said, "that social networks are being mined for every bit of data that can be collected there. Marketers are interested not merely in the information that users put there themselves, which is substantial, but even more so, what they're doing on the site, and now off it as well."

Montgomery said that one line in Zuckerberg's post is particularly telling: "If you select that you don't want to share some Beacon actions or if you turn off Beacon, then Facebook won't store those actions even when partners send them to Facebook." Just because Facebook isn't storing the data doesn't mean that it and its partners aren't analyzing user activity.

"The data that is being gathered and mined," Montgomery said, "is going to lead to marketing on steroids. Companies are increasingly engaging in extensive, highly manipulative marketing, and the more data that they have about particular individuals, the more intense that marketing will be."

What is needed, Montgomery argued, is for regulatory bodies in both the U.S. and Europe to take a much closer look at the privacy and marketing issues raised by social networking sites.