I've blogged a few times about the extensibility of IIS7, but here is a real world example that provides a really concrete idea of the real possibilities: Vince Bonfanti just announced end-to-end BlueDragon/CFML integration with IIS7 including core server, configuration, and administration tool integration!
Did you ever think you'd see a day when developers could write CFML (ColdFusion Markup Language) that can plug-in natively to the core IIS pipeline and do things like request filtering, logging, and more for all types of requests? Did you ever think you'd see first class support for CFML configuration and administration UI integrated with IIS? With BlueDragon and IIS7, it is a reality.
In Vince's first post, he describes the integration his team has done with IIS7's new pipeline which enables developers to hook into new Application.cfc event handlers and do things never before possible with CFML. Bruce shows a <20 line code sample of how to prevent people from stealing images from your web site by "hot linking" to your content.
In his second post, Vince describes how they have now integrated BlueDragon's configuration into the new IIS7 configuration store, allowing developers to now store IIS and CFML configuration in the same file, and enjoy all the same benefits of distribution configuration and xcopy deployment.
Last, Vince describes in his third post how they have also integrated BlueDragon into IIS7's administration tool, providing first class support for Administrators to manage BlueDragon. Here is a quick screen grab of the new BlueDragon administration features: