What is it?
IronPython is an implementation of the Python programming language and is running under .NET and Silverlight.
How does it work?
When you run a .NET program written in a language such as C# or VB.NET, your code gets compiled to Intermediate Language (IL) code.
IronPython contains the code and classes for IronPython itself, including the IronPython interpreter. When you run the IronPython interpreter, you are running the IL code for IronPython itself.
More simplistic, the classes you create in your Python code are created dynamically at runtime.
This release numerous bug fixes, also includes a IronPython Tools for Visual Studio, support for extension methods and more...
You can see more on official site.