Source SDK Now Updated

Future Source SDK updates will provide new development tools, as well as source code for creating single and multi-player mods
Valve has announced the release of a new version of Source SDK which includes new content and tools to create custom game experiences for Half-Life 2: Episode Two, Portal, and Team Fortress 2. In addition to support for games in The Orange Box, the Source SDK can continue to be used to create content for other Source engine-based games, such as Half-Life 2: Episode One and Counter-Strike: Source. The update is available now via Steam.