<center></center> We have had plenty of people asking about the L4D2 Beta showing up in their steam catalog. So in case you missed it or were confused, here is some more info.
Currently, changes to L4D2 will first appear in the Beta before they appear in the main game. The Beta will change often. This mean this build is very active so you might want to avoid it if you have bandwidth caps. Today we released another update for it. You can read the release notes for the update here.
Right now the Beta is the only place you can play L4D2 on Linux natively. If you run Linux, load it up and give it a try. If you have problems, let us know. You can post here and share your experience.
While the biggest changes are for Linux, those changes actually have the possibility to impact Mac and Windows players as well, which is why it is helpful for even non-linux players to test the Beta.
The Beta also contains an update to the Authoring Tools to allow you to work in the new EMS[www.l4d.com]. These tools are only available for Windows users and only currently available in the Beta. You can check the developer wiki here for more information.
While the tools are only available on Windows, everyone in the Beta can play the new EMS content.
We do not have servers running for the Beta yet as we concentrate on client issues and fixes but the server code has been released and is working - so let us know if you have any issues with Windows or Linux servers. We will be rolling out our own dedicated servers in the near future.