Upwards of 90 percent of "hacked" Facebook accounts don't get compromised on Facebook, the company once told us. Yet, since Facebook has become one of the most important destinations for posting links, the company has been forced to protect its users from external threats as well as internal ones. Facebook today announced that its URL blacklist system that protects users from nefarious websites now incorporates the massive URL blacklists of Microsoft, McAfee, Sophos, Symantec, and Trend Micro. If Facebook decides that a link you've clicked could be malicious, it warns you — now, its database of bad links just got a whole lot bigger.

While Facebook's URL blacklist is extensive, its scale will benefit greatly from the new partnership. Trend Micro, for example, has built up a huge database of malicious URLs and links — it alone scans 300 million URLs and blocks 1.4 billion potential threats per day. Part of the reason this is important is because, as we noted earlier, most "hacks" occur outside of Facebook where you might accidentally type in your password.

Alongside the blacklist update, Facebook today launched the AV Marketplace, a new home for free six-month trials of apps like Norton Anti-Virus 2012, Trend Micro Titanium Security Essentials (PC), and Trend Micro Smart Surfing (Mac). While McAfee has offered six-month trials in the past, this marks the first time Trend Micro or Symantec has offered this kind of deal. "We believe that arming our users with antivirus software will help empower them to stay safe no matter where they are on the web," Facebook said.