If you're waiting on a new release of the Visual Studio 2005 SDK, v3 (September 2006) is now available for download from http://www.vsipmembers.com/.
The September 2006 v3 RTM is the next milestone in the VS 2005 SDK. The v3 release contains the final release of the DSL Tools v1, contents and samples for Team Foundation Server and Team Test extensibility, IronPython website and web project samples, 5 new Visual Studio PowerToys, managed parser & lexer generator tools (MPPG/MPLEX), updated documentation and many more IDE integration samples. Note that the VSTA runtimes and documentation are still in pre-release form and they are not included in this release. This release of the SDK also includes important changes to the end user license agreement regarding platform targeting restrictions; please refer to the EULA shown in the VS SDK Setup for more details.
You can also find the documentation online: Visual Studio SDK Now Available in MSDN Library Online.