Microsoft has released HPC Pack 2008 R2 SDK with Service Pack 3

The Microsoft HPC Pack 2008 R2 SDK with Service Pack 3, and its supplements, are designed to provide the tools and content necessary to write parallel applications for the Windows HPC Server 2008 R2 platform.
The Development Kit consists of several components:

Required: The Microsoft HPC Pack 2008 R2 SDK core package can be used to write client applications that interact with the job scheduler. Install this from sdk_x64.msi or sdk_x86.msi. You will need the HPC Pack 2008 R2 Client Utilities installed as well, those are available through the full HPC Pack 2008 R2 installer or through the Client Utilities redistributable available in the related downloads. This updated SP3 SDK supports new features available with HPC Pack 2008 R2 SP3-based clusters. Applications built with this SDK will work on pre-SP3 clusters as long as they do not use new SP3-specific features.
Files: sdk_x64.msi, sdk_x86.msi
Optional: The main Sample Code package provides a number of examples that to help you learn how to write applications that interact with or run on an HPC cluster.
Files: HPC2008R2.SampleCode.zip
To develop MPI applications you need the HPC Pack 2008 R2 MS-MPI redistributable installer, available through the related downloads.

For complete details on the SDK, visit the Microsoft High Performance Computing section of MSDN: http://msdn.microsoft.com/en-us/library/aa496121.aspx

  HPC Pack 2008 R2 SDK with Service Pack 3