Counter-Strike: Source
* Removed FCVAR_ARCHIVE from cl_minmodels
* Added a workaround for linux servers sometimes being frozen after changelevel
* Linux dedicated server -condebug captures all console output now
* Fixed an exploit when joining a team that could spawn live spectators
* Fixed mp3 player advancing more than 1 song during level transitions

Half-Life 2

* Fixed bug where NPCs would ignore hintbrushes that should block line of sight

Source Engine

* Fixed really long game directories not being able to upload game statistics
* Fixed listen server host not being able to hear sounds from bsp .zip files
* Fixed demo smoother not being able to select samples in certain demo files
* Fixed partial-HDR exploit in DX7 allowing wireframe materials

source: steampowered.com