Source SDK Update Released
Product Update    - Valve 11 May 2010
Updates to Source SDK have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Source SDK
The Source SDK was updated today to fix tool problems for some games and mods. We are sorry for the disruption to your work that the SDK issues may have caused for the past week. Thanks very much for your patience.

SDK Launcher

The terminology for Engine Version has changed and now maps to the year of release rather than to particular products. Here are the options now present in the list of engine versions along with the games which utilize them:

Source Engine 2006
Half-Life 2
Counter-Strike: Source
Half-Life 2: Deathmatch
Half-Life 2: Episode 1

Source Engine 2007
Half-Life 2: Episode 2

Source Engine 2009
Day of Defeat:Source
Portal
Team Fortress 2

Please note that you may need to re-create the game configurations for total conversion mods that were built using 'Source Engine 2007'. Simply run the 'Edit Game Configurations' utility to do this.

Valve games should show up under the appropriate engine version. If they do not correspond to the list given above then you can either manually edit the configurations or run the Reset Game Configurations utility.

SDK Tools
There are now tools supporting three versions of Source in the SDK distribution. If you are creating content for a game or total conversion based on 'Source Engine 2007' you may need to run some of the command-line tools now located at:
sourcesdk\bin\source2007\bin
The command-line tools needed for 'Source Engine 2006' and 'Source Engine 2009' are still located at:
sourcesdk\bin\ep1\bin
and
sourcesdk\bin\orangebox\bin



People can start their work again !