Mr. Zuckerberg, via Facebook

CEO Mark Zuckerberg wrote a blog post late yesterday, responding to user concerns about a recent update to Facebook's Terms of Use (casually labeled "TOS" for "terms of service").

The TOS, changed on February 4, stipulates that Facebook owns all content uploaded onto the site, including material posted by users that shut their accounts down after February 4. The company also reserves the right to sublicense the content as it sees fit.

"Our philosophy is that people own their information and control who they share it with," Zuckerberg wrote yesterday. "When a person shares information on Facebook, they first need to grant Facebook a license to use that information so that we can show it to the other people they've asked us to share it with. Without this license, we couldn't help people share that information."

According to Zuckerberg, issues raised regarding the revised TOS stem from demands from users that naturally conflict, rather than a perceived desire by Facebook to sell content to marketers:

People want full ownership and control of their information so they can turn off access to it at any time. At the same time, people also want to be able to bring the information others have shared with them—like email addresses, phone numbers, photos and so on—to other services and grant those services access to those people's information.

These two positions are at odds with each other. 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.

Zuckerberg also assured users that "[Facebook] wouldn't share your information in a way you wouldn't want," and concluded thus:

We're at an interesting point in the development of the open online world where these issues are being worked out. It's difficult terrain to navigate and we're going to make some missteps, but as the leading service for sharing information we take these issues and our responsibility to help resolve them very seriously.

The CEO vowed that the resolution of such issues would be "a big focus for [Facebook] this year."

On microblogging site Twitter, a number of disgruntled users expressed an inclination to shut their Facebook accounts down. It is unclear how many actually did so. But a Facebook group protesting the revised TOS, which numbered fewer than 600 members yesterday, has swelled to nearly 22,700.

Recent comScore data found Facebook visitors numbered about 221 million by December 2008 — nearly closing the gap between itself and Google-owned Blogger, whose visitors numbered 225.5 million at year's end. (In terms of unique visits, last year Blogger topped the charts among social media sites.)

That difference — 4.5 million users — is a dramatic shift from the 21 million user gap in November, which means Blogger grew relatively little in a month, while Facebook expanded incrementally.

"Assuming Facebook's upward trend continued in January (and Blogger's remained flat), the social network sits on top of the roost now," TechCrunch observed.