It also allows for a more general extensible architecture, where part of the application is written in IronPython and it can also be extended with IronPython.
One application that takes this approach is Intellipad, an editor that is part of the Microsoft Oslo framework.
Another editor that takes a similar approach is the newly created MetaNote editor, the brainchild of Leon Bambrick:
MetaNote is a text editor. Ultimately, MetaNote intends to be the most versatile editor imaginable. See that button in the toolbar? Right click on it, and edit the code behind it. Don't like the way 'Find' works? -- right click on it, and edit the code. Need a new button in the toolbar? So add it already, with a single click. Share packs of extensions and macros with other users. Everything in MetaNote is under your control, effortlessly, at runtime.MetaNote is open source, with a Google Code Project Page where you can checkout the sources or download a binary release.