In addition, Facebook is offering both toolbars in 16 new languages: Arabic, Chinese (simple and traditional), Danish, Dutch, German, Spanish (Spain and international), French, Hebrew, Indonesian, Italian, Japanese, Portuguese (Brazilian), Swedish and Turkish. Previously, the Firefox toolbar was only available in English.
The toolbars provide links to various Facebook sections, including the user's home page, inbox and friend profiles, and display the number of friend requests, inbox messages, status updates and invitations the user hasn't yet checked out. With the toolbar, Facebook users can also share content with their friends and upload photos.
Facebook is also simultaneously releasing the source code for both toolbar versions, so that developers can modify and adapt them as they wish.
The IE toolbar is the latest move by the company to let its members interact with Facebook when they aren't on the site. For example, Facebook has started allowing members to post messages to the site via email.
Not that Facebook is anywhere close to suffering from a lack of user engagement. On the contrary, usage metrics for Facebook rose significantly across the board in 2009, compared with 2008, comScore reported last week.
For example, unique visitors in the US reached almost 112 million last December, up 105 percent compared with December 2008, making Facebook the fourth-most-popular site in the country.
Also, on average, 37.7 million people visited the site per day, up 181 percent, and viewed a total of almost 45 billion pages during the month, up 151 percent.
Overall, Facebook users spent almost 28 billion minutes on the site, almost triple the time in December 2008 and giving Facebook a seven percent share of time spent online in the US in general.
Total visits more than tripled to almost 3.1 billion, comScore said.
See also: Fake antivirus scam hits Facebook