Michael Foord http://www.voidspace.org.uk/ironpython/hosting_api.shtml
Business rules stored as a Python or Ruby backed Domain Specific Language could be extremely useful - they can be read / written by business managers, rather than programmers, and even changed at runtime.
.NET 4 offers the dynamic keyword in C#, which makes it much easier to use DLRs like IronPython.
This is an example of coding C# dynamically:
C# 4 supports named parameters and optional parameters, to make it easier to call Office methods.