The latest Community Technology Preview (CTP) release of Windows HPC Server 2008 is live at the beta program community site (http://Connect.Microsoft.Com). If you aren't yet a registered beta program participant, then you'll first need to join the program using the same web site.
This CTP release includes the HPC Pack which may be installed on any x64 edition of Windows Server (an evaluation version is also available for download) as well as the HPC Pack SDK (for developing HPC applications) and the HPC Pack OPK (for OEMs preparing HPC offerings). Be sure to provide feedback on the CTP features using the Feedback Tool on the Connect website. Also, please leverage the HPC MSDN Forums to obtain product support for ITPro's and Developers (http://forums.microsoft.com/WindowsHPC).
Source:→ Windows HPC Server 2008 Team Blog
Microsoft, Windows HPC Server, HPC Server 2008, CTP, Preview, Download