As part of my Gamefest 2011 presentation Modern Texture Content Pipelines (US / UK), I demonstrated the "DirectXTex" library which is a shared source implementation of DDS file I/O (including the "DX10" header extension), texture content processing operations (resize, format conversion, mip-map-generation), software block compression (BC1 - BC7), height-map to normal-map conversion, and a simple .TGA file reader and writer.
The attached package includes:
See the ReadMe.txt file in the package for more details.
Note: There is another version of the Texconv sample with the DirectXTex library that uses DirectXMath with DXGI 1.2 support available on the Windows SDK Samples Code Gallery. It can be built using either Visual Studio 2012 or VS 2010 with the new Windows SDK. There is also a Windows Store app (a.k.a. Metro style app) version of the DDSTextureLoader there as well. The Windows SDK Samples Code Gallery version of DirectXTex can be made to run on Windows Vista and WIndows 7 by adding _WIN32_WINNT=0x0600 to the Preprocessor Definitions.
Update: DirectXTex is now hosted on Codeplex. The latest version of the library, documentation, notes on future work, release history, and other information is now available there.