DirectX 12: This preview includes the headers and libraries needed to build DirectX 12 (as well as Direct3D 11.3, DXGI 1.4, and Direct2D/DirectWrite 1.3) applications for the Windows 10 Technical Preview (build 10041). For better support including access to pre-release samples and documentation, join the DirectX Early Access program. Also, check out this post on the DirectX Developer blog.
CodePlex/GitHub: Project files for both Windows desktop apps and universal Windows apps using VS 2015 are available for DirectX Tool Kit, DirectXTex, and DirectXMesh. Note that currently DirectX Tool Kit's
GamePad class is a 'null' device for universal Windows apps as both the XInput compatibility library and the new gamepad API for universal Windows apps are not yet in the preview Windows 10 SDK.
Update: With the release of flight 10130, the
GamePad class in DirectX Tool Kit makes use of the new
IGamePad WinRT class for universal Windows apps. Note that this API currently supports Xbox 360 Common Controllers, but does not yet support Xbox One Controllers in this flight.
DirectXMath: This Windows 10 SDK preview includes DirectXMath 3.07 which addresses a number of known issues in version 3.06.
Related: Windows 10 Technical Preview