The kit includes drag 'n drop Controls and Components, SmartTags, VB.Net and C# source code for all tools and samples as well as complete QuickStarts, APIs, and documentation.
IronPython Studio is a free full IDE for the Python programming language based on the existing IronPython example and the Visual Studio 2008 Shell runtime ... and doesn't need Visual Studio installed
Pex (Program EXploration)
is an intelligent assistant to the programmer.
By automatically generating unit tests, it helps to find bugs early.
In addition, it suggests to the programmer how to fix the bugs.
Pex is actually a unit test generation tool. It takes a parametrized unit test and generates parameter sets to get full code coverage and exercise all of the code. It actually analyzes the code to find appropriate values, and then generates normal (unparametrized) tests.
ASP.NET MVC provides model-view-controller (MVC) support to the existing ASP.NET 3.5 runtime, which enables developers to more easily take advantage of this design pattern. Benefits include the ability to achieve and maintain a clear separation of concerns, as well as facilitate test driven development (TDD).
WPF, in conjunction with the .NET Framework add-in model, allows you to address a wide variety of scenarios that require host applications to display UIs from add-ins.
Addins (plugins) for WPF can even do UI. I'm not convinced this is necessary to do UIs with plugins, but it's necessary if you want to allow untrusted code to do it.