As promised earlier this week, the Left 4 Dead 2 Linux beta is live. The beta build allows Linux owners to play the game natively, and comes with the new Extended Mutation System. Those who currently own Left 4 Dead 2 will see the beta in their Steam library, and the complete game comes with authoring tools and the beta Dedicated Server. It also includes updated Windows and Mac clients, so even if you are not running under Linux you can help by testing the Beta. Further information can be found through the link to the L4D Blog.