Facebook has been forced to make a major about-face on its controversial new Beacon ad program after more than 50,000 users signed a petition objecting to the initiative. Beacon sends messages to users' friends about their purchases on sites like Travelocity, Blockbuster, eBay and Fandango. According to The New York Times, the petition's signers want to be able to opt out of the program completely with one click.

After the uproar, the company announced late Thursday that it was amending its policy and would no longer send messages about users' activities without getting explicit approval each time, the Times reports. The move by the site, which has more than 50 million active members, brought praise from a spokesperson for MoveOn.org, the political action group that started "Petition: Facebook, stop invading my privacy" 10 days ago.

"Before, if you ignored their warning, they assumed they had your permission [to share information]," explained MoveOn spokesperson Adam Green. "If Facebook were to implement a policy whereby no private purchases on other Web sites were displayed publicly on Facebook without a user's explicit permission, that would be a step in the right direction."

Facebook was created as a free social-networking site for Harvard students by 23-year-old Mark Zuckerberg while he was an undergrad at the university in 2004 and has since expanded to allow access to anyone over 13. It has grown into one of the biggest social-networking sites on the Internet, and the Times said the roll-out of Beacon was an attempt by the company to figure out how to translate its popularity into profits. Unlike companies like Google and AOL, which regularly track users' online actions and then send them ads based on the searches they've conducted and sites they've visited, Facebook was trying to make its tracking system more transparent by sending news alerts to friends about what their friends are buying and viewing online.

Among the complaints from users, according to the San Jose Mercury News, were that Christmas purchases they made instantly became known to the friends who might have been the intended recipients.

Though they agreed to change the policy, Facebook executives said the people who complained were a marginal part of the site's user base. A month ago, when Zuckerberg introduced Beacon during a visit to New York, he predicted that over time, users would accept Beacon, which Facebook executives see as an extension of the kind of book and movie recommendations that members regularly make on their profile pages already.

Given the uproar last year over the introduction of the News Feed function, which drew protests from more than 700,000 users over its ability to track friends' Facebook movements minute-by-minute, this latest flap is part of the process of innovation, according to one of the company's vice presidents.

"Whenever we innovate and create great new experiences and new features, if they are not well understood at the outset, one thing we need to do is give people an opportunity to interact with them," Chamath Palihapitiya told the Times. "After a while, they fall in love with them."

Palihapitiya initially said Facebook would not add a universal opt-out to Beacon, which is what many of the protesters have requested. An opt-out box pops up for a few seconds before the information is sent out to friends, but users have complained that it is hard to find and appears for only a few seconds. Palihapitiya said Facebook will make the boxes larger and have them remain on the page longer.

Later in the day, the company issued a second statement saying, "No stories will be published without users proactively consenting." Users will now have to click an "OK" button on a notification box on their Facebook page before information about a purchase is sent to their friends.

Though Facebook has gained notoriety for the ease with which its users post potentially embarrassing or highly personal information, the activity-tracking by Beacon has still rubbed some members the wrong way. "We know we don't have a right to privacy, but there still should be a certain morality here, a certain level of what is private in our lives," Tricia Bushnell, a 25-year-old Los Angeles native and longtime Facebook user told the Times. "Just because I belong to Facebook, do I now have to be careful about everything else I do on the Internet?"

In addition to the user protest, the paper said two privacy groups announced this week that they were preparing to file privacy complaints about Beacon with the Federal Trade Commission, and Overstock.com has pledged to stop running Beacon on its site until it becomes an opt-in program.