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.
supports Debian linux based system and RPM based, tested in Ubuntu 11.04 Natty Narwhal
That’s it, Now invite people by adding circles and start hangout.
Also check Hangout settings for Camera and sound options.