What keeps Facebook executives up at night? Close scrutiny of how the company manages its members' information, apparently. Facebook chief executive Mark Zuckerberg posted a blog this morning (at 1:17 A.M. Pacific time) on his company's site explaining that he and the rest of the Facebook brain trust are rethinking changes they had made earlier this week to the site's terms of use. (Here's a link to the Facebook terms of use.) The changes caused a backlash among Facebook members who perceived the company's new terms of use claimed ownership of members' personal information. Of particular concern is what the company does with member information after that member has canceled his or her membership with Facebook.

The company's solution, for now, is to revert to the September 23, 2008, version of the terms of use, which aren't much different than the February 4 terms that caused the uproar. The terms still indicate that Facebook can make copies of member content and, even if a member removes content from the site, Facebook can still retain archived copies of that information. Facebook isn't claiming to own that information, but it isn't promising to delete that info either.

In his early Wednesday morning blog, Zuckerberg acknowledged confusion among Facebook members over the site's terms of use. (Read Zuckerberg's blog post.) Facebook is, for now, reverting back to its previous terms of use and "in the next few weeks" will create a new version that will be "a substantial revision from where we are now," he wrote. He also promised that, "since this will be the governing document that we'll all live by, Facebook users will have a lot of input in crafting these terms."

A message sent to Facebook members when they logged in on Wednesday crystallizes the nagging privacy issue that the site must address: Although Facebook says it will not share member information "with anyone" once a member deactivates his or her account, the message also states, "If you've already sent a friend a message, they'll still have that message." Zuckerberg in his February 16 blog (read it here) chalked the issue up to a lack of technology. "There is no system today that enables me to share my email address with you and then simultaneously lets me control who you share it with and also lets you control what services you share it with," he wrote.

Although Facebook is a closed site that allows members to control who sees their information, once that information is shared, it can take on a life of its own beyond the member's control (a situation not unlike the Web as a whole). As info security specialist Herbert Thompson pointed out in his Scientific American.com column "How I Stole Someone's Identity" last year. "It's also critical to remember that once you put data online, it's almost impossible to delete it later. The more you blog about yourself, the more details you put in your social networking profiles, the more information about you is being archived, copied, backed up and analyzed almost immediately. Think first, post later."

A more blatant example of a Web site attempting to "own" someone else's property is that of the medical blog aggregation site Wellsphere.com, according to the blog Better Health. (Thanks to ePatientDave, who alerted Scientific American.com to this issue via Twitter.) Wellsphere.com's terms of use indicate that content (including comments, ideas, photos and videos) given to the company to be posted on its site gives Wellsphere "full rights of ownership." (Here's a link to the Wellsphere terms of use.) The 1,700 bloggers who sent their writings to Wellsphere granted the company (since January owned by The HealthCentral Network, Inc.) a royalty-free, paid-up, exclusive, worldwide, irrevocable, perpetual license to the material, which Wellsphere can reproduce, distribute or create derivative works of without further compensation to the bloggers. Now that Wellsphere is part of HealthCentral, many bloggers who contributed to the site are wondering what will happen to the content they contributed. (See a list of tweets from nonplussed bloggers here.)

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