Don’t let the “R2” name fool you, there’s a lot packed into Windows Server 2008 R2.  Head over to the ISV team blog to see how to get started leveraging Windows Server 2008 R2 features.  For instance, I found out that you can you use the Windows 7 SDK on Windows Server 2008 R2 because they’re both based on the same kernel.  You can also use the SDK with Visual Studio 2008, including the Express editions.