This update prevents annoying and abusive server admin from screwing around with your CS: S client settings.
Counter-Strike: Source

Fixed a crash which could occur if the dynamic weapon price list failed to download
Source Engine

Added new cl_restrict_server_commands to prevent unwanted commands being run on game clients. The default value is 1, valid settings are:

0 = Don't restrict any server commands

1 = Restrict server commands in Valve multiplayer games

2 = Restrict server commands in all multiplayer games

Decreased startup time in some cases by rate-limiting the packets sent to clients during logon

Improved responsiveness when entering map areas with lots of entities by automatically compressing large packet updates