Vonage has launched a new mobile app for calling Facebook friends. Users can make free mobile calls to their Facebook friends who also run the app (anywhere in the world). This can be done right from their friends list with one touch.

"The Vonage Mobile app for Facebook is a tangible example of our commitment to deliver extraordinary value and a better communications experience for individuals and their social networks, across broadband-enabled devices, around the world," says Vonage Holdings CEO Marc Lefar. "This is just the start. In the future we will expand on this service to include a wide range of integrated voice and messaging services that change the way people communicate."

Just download the app from the appropriate app market, enter you Facebook log-in info one time, then view your FB contacts once the app automatically detects them. Friends will be grouped by those who can be called for free and those who are available for instant messaging.

This might be helpful in itself, at least for Android users, because the new Android app update Facebook just launched still lacks a chat feature.

The app itself is free, and is available for iPhone, iPod Touch, and Android devices. It works over Wi-Fi and 3G/4G networks in most countries.