As expected, Facebook has announced Skype-powered video calling for its users, who now number more than 750 million according to the company. The new feature was unveiled by Facebook CEO Mark Zuckerberg and Skype CEO Tony Bates at a news conference at Facebook HQ on Wednesday where Facebook engineer Philip Su provided a walkthrough of the application. The social networking giant also launched a new chat sidebar and what Su says is one of the site's most requested features in multi-person chat.

Facebook video calling won't require users to set up a Skype account but will require a one-time setup. This will be triggered the first time someone attempts to call you or you attempt to call someone by clicking the 'Call' button that now appears between the 'Message' and 'Poke' buttons on a friend's profile or at the top right of a chat window. Users can also leave a video message if the call recipient doesn't respond.

The site will be rolling out video calling in over 70 languages over the next few weeks, but if you don't want to wait you can install it now by heading here. The application runs on Firefox, Chrome, Internet Explorer and Safari, but isn't compatible with Linux and won't make its way to Facebook mobile apps.

On his Facebook Blog post describing the new feature, Su said, "Video chat has been around for years now, but it's still not an everyday activity for most people. Sometimes it's too difficult to set up, or the friends you want to talk to are on different services. So a few months ago, we started working with Skype to bring video calling to Facebook. We built it right into chat, so all your conversations start from the same place."

With Microsoft an investor in Facebook since October 2007 and the two having already collaborated on a number of projects, the "few months ago" referred to by Su coincides nicely with Microsoft's announcement two months ago that it was acquiring Skype for US$8.5 billion. Zuckerberg said that although he would have had no problems dealing with Skype was an independent company, Microsoft's ownership provides a sense of stability with a company Facebook can trust.

This week also saw Facebook launch a new chat sidebar that adjusts with the size of your browser window and automatically appears when the window is wide enough. It lists the people you message most, whether they are online or not. Alongside this was the launch of a multi-person chat feature that allows more friends to join a conversation by selecting Add Friends to Chat.

With Google taking a stab at the social networking pie with Google+, which was launched last week and also includes video chat along with a group video chat feature called Hangouts, the addition of a video calling feature on Facebook is even more important.

When asked if Facebook would be adding a group calling function like Hangouts, Zuckerberg responded saying, "I wouldn't rule anything out, but I also wouldn't undersell what we've rolled out today," noting that one-to-one chat makes up the majority of video chatting online today. "As far as the Google stuff goes, I'm not going to say a lot about Google+ obviously."

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