I have an affinity for python, but I work in a .NET environment, so I was looking into Iron Python, and wondering what it would be used for.  
Could you write an app in it? or is it for adding a scripting language to your app?
How do you guys use it?
Either or both :)
I wouldn't claim to know a specific "purpose" for IronPython but it certainly can be used to write applications, and it can be used for scripting within a larger .NET application.
Aside from anything else, it's a handy way of gently easing Python developers into the world of .NET. (Why not learn C# at the same time? Come on in, the water's lovely...)
Iron Python : what are good uses for Iron Python