Sorry to sound so vague, but I have to start by saying that Windows Server 2008 is a server platform, not a cure for cancer, so lets put it in perspective and set our expectations high, but not stupidly high expecting it to be revolution.  Server 2008 is a quality evolution of Windows Server 2003 and extends and enhanced the Server 2003 offerings.  However, if you plan on building applications for the future then Server 2008 will be the place to be.

Microsoft have released a document called the "Windows Server 2008 Developer Story" that has a wealth of information on Server 2008 developer directions and how they combine to offer something greater than the sum of the parts.  The download site describes itself as:

Windows Server 2008 Developer Story

An executable containing the Windows Server 2008 Developer Story

The Windows Server 2008 Developer Story introduces users to new features of the Windows Server 2008 operating system by providing a cohesive story about how the features fit together to make a compelling platform for developers. The Developer Story topics explain how to take advantage of a new feature or solve a problem using the new Windows technologies. The topics include conceptual information for context and technical specifications for practical application of each scenario.
This download contains the Windows Server 2008 Developer Story (ServerDevStory.chm).

Download details: Windows Server 2008 Developer Story

If you look inside the help file it loads then you get this list of the top 7 ways to take advantage of Windows Server 2008. 

Top 7 Ways to Light Up Your Apps on Windows Server 2008

Whether you are building Web applications or writing core server-based system services, Windows Server® 2008 provides many new features that you can leverage to build more secure, flexible, and innovative applications.

1. Build More Flexible Web Applications on Internet Information Server 7.0 (IIS7)

   • Extend IIS7 through modules

   • New unified configuration model

   • Administration capabilities using Microsoft.Web.Administration Managed API

2. Build Connected Systems

   • Windows Communication Foundation

   • Windows Workflow Foundation

   • Windows Process Activation Service

   • Microsoft Message Queue 4.0

3. Develop Federation-Aware Applications

   • Active Directory Federation Services

   • Active Directory Lightweight Directory Services

   • Windows Authorization Manager

4. Design Highly Manageable Applications

   • Windows Eventing 6.0

   • Windows Installer 4.0, ClickOnce

   • Windows PowerShell™, Microsoft Management Console 3.0, and Windows Task Scheduler 2.0

5. Develop More Reliable Applications

   • Application Recovery and Restart API

   • Restart Manager

   • Transactional NTFS, Transactional Registry, and Kernel Transaction Manager

6. Build Scalable Applications

   • Thread Pool API enhancements

   • Thread Ordering Service

   • Wait Chain Traversal

7. Leverage Virtualization on Windows Server 2008

   • Server Consolidation

   • Business Continuance

   • Testing and Development

   • Branch Office

The information presented here and in the downloadable compiled help (.chm) file is designed to help developers prepare for Windows Server 2008.

As an example, we have sample extensions to the IIS7 administration page as shown below:

My IIS 7.0 Administration UI Extension Page

The UI extension option in IIS 7.0 is an exciting feature for any .Net developer. You can write your own custom UI pages and can add various features to it to manage IIS on Windows Vista and Windows Server 2008. I have written an UI extension and is attached with this post.

ttfn

David