Are you getting the below error when installing Windows Management Framework 3 on your Windows 2008 SP2 Server?

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Well, all you need to verify is the current version of your .NET Framework.  To verify the current version; proceed to the registry

HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP

The branch is most likely only upto V3 or V3.5

Download and Install .NET Framework 4 and your system will be ready to Install the Windows Management Framework 3

You may also find below post useful

http://www.happysysadm.com/2012/06/upgrading-to-powershell-30-on-windows.html