Today I spoke at the Heartland Developers Conference on why ASP.NET developers should care about Windows Server 2008. If you were at the session or just want to know more about what's in store for you as an ASP.NET developer, check out the following resources.
Windows Server 2008 Developer Training Kit - this set of Hands-on-Labs and PPT files demonstrate several of the features you can take advantage of on the Windows 2008 platform. There are labs for Transactional NTFS, Windows Eventing 6.0, Powershell, IIS and the .NET 3.0 framework technologies. The IIS lab will help you build a managed-code module to extend the IIS pipeline as well as an UI extension for the new IIS Manager. There are additional examples on IIS.net for developer extensions for IIS and manager.
If you are interested in the self-hosting capabilities of IIS7, there is an article in the MSDN library called Creating a Hosted Web Core Application. In addition, there is an API reference. One example of why you want to do this is to create isolated testing configurations for your web applications including all of the managed and native pipeline modules.