Google+ is a new social network powered by Google Inc, so far Google Plus is a available for limited number of users and you can get your Google+ invitation if you have a friend already using Google+ social network.
Google Plus Hangouts Walkthrough Preview
Hangouts is a new video chat feature in Google+ allows you to chat with people added to your circles with 10 people maximum number for video chatting for each hangout. Google+ Hangouts works in Linux, Mac OS X and Microsoft Windows.
If don’t already have Google talk plugin, Google+ Hangouts won’t work. Install Google talk plugin from Here. “supports Linux, Mac, Windows”
Install suitable package for you system.
[note]supports Debian linux based system and RPM based, tested in Ubuntu 11.04 Natty Narwhal[/note]
That’s it, Now invite people by adding circles and start hangout.
Also check Hangout settings for Camera and sound options.