As Facebook continues its fight with the Federal Trade Commission over the site's much-maligned privacy policies, the social media behemoth has publicly acknowledged that they do indeed actively track the web surfing habits of their over 700 million registered users.

USA Today is reporting that Facebook keeps a running log of the websites each Facebook user has visited over the previous 90 days. Using cookies similar to those employed by Google and Adobe, Facebook has been routinely collecting information that can prove invaluable to online retailers.

The paper reports that Facebook tracks its users' online movements through two distinct cookies: browser cookies and session cookies. As reporter Byron Acohido explains, "Each time you visit a third-party webpage that has a Facebook Like button, or other Facebook plug-in, the plug-in works in conjunction with the cookie to alert Facebook of the date, time and web address of the webpage you've clicked to." If that weren't enough, the cookie also helpfully records your IP address and operating system among other pieces of information.

The fun part of this technology is that even if you are not a Facebook member, simply by visiting the site you will receive the cookie. Non-members receive the "browser cookie" which simply records what sites the user has visited; members get the full "browser cookie" treatment... IP address recordings and all!

"Facebook could be tracking users without knowledge or permission, which could be an unfair or deceptive business practice," Rep. Ed Markey (D-MA) told USA Today. He and Rep. Joe Barton (R-TX) co-sponsored a bill aimed at limiting online tracking of children. 

Following the appearance of Facebook CEO Mark Zuckerberg on The Charlie Rose Show last week, Markey and Barton sent a letter to the Facebook founder asking him to explain a recent U.S. patent application by the site for "technology that includes a method to correlate tracking data with advertisements." Zuckerberg was given until December 1 to respond to the inquiry.

Internet privacy advocates have had a long and contentious relationship with Facebook, regarding the social network's privacy measures as somewhere between confusing and deceptive.

With this recent acknowledgment by Facebook that it is indeed keeping tabs on the personal information of users that has not been willingly volunteered, the site's critics will surely be heard from. As for Facebook and the site's millions of users, the inevitable question now becomes "What's next?"