"We have created a linux client for the current Steam Beta. If you wish to run a beta server under linux then you can download the client from:
ftp://ftp.valvesoftware.com/Linux/steam

server: ftp.valvesoftware.com
user: hlserver
password: hlserver
directory: Linux/steam

This directory contains two files, "Steam_README.txt" which details how to use the tool and "steam.gz" which can be unzipped (via gzip -d "steam.gz") to extract the "steam" binary. You should copy this binary to an existing hlds_l directory (any version) and then use "steam" binary to update it to the Steam beta version (the Steam_README.txt file tells you how to do this).

Please note that this is a beta release and we would appreciate you reporting any bugs you may encounter. Please include details such as the exact linux kernel and linux distribution you are using (or the FreeBSD
equivalents). "


Changelog (vs 3.1.1.1)
------------------------
See: http://www.steampowered.com/platform/update_history/dedicated%20server.html
Plus:
- Optimised tracelines, this should significantly improve performance for mods using 9-way blending (i.e CStrike and DoD).