Source: HalfLife-2.nlHalfLife-2.nl posted the news that some HalfLife2.net Forum visitors noticed that the next update of steam, release date November 5th, would feature:
Full Change History:[-] November 05, 2004 (current release)Changes/Additions------------------------Hammer Half-Life Model Viewer Content compiling tools DocumentationCheck it for your self here. A small error or can we expect to see the release of the Half-Life 2 SDK today? Time will tell.