The latest version of PowerShell, version 5.1 was released for WS2012R2, WS2012, W8.1, W2008R2, W7 SP1 on 1/19/2017. The WMF 5.1 version of PowerShell is already running in WS2016 and W10 machines.

Release Notes
Install and Configure

WS2016 and W10:

1. Installation for WS2008R2 (and W7 SP1)

Overview:
Install .NET Framework 4.5.1 (if required) > Restart > Verify Installation
Install WMF 5.1 > Restart > Verify Installation

1. Have all current Windows updates installed on 2008R2 SP1 machine

2. Download the WMF5.1 Package and Prerequisites for W2008R2, choosing 32 or 64 bit options.

• x64:Win7AndW2K8R2-KB3191566-x64.ZIP
  x86:Win7-KB3191566-x86.ZIP
• NET Framework 4.5 exe setup file
• The zip file contains an MSU file and the PowerShell script file Install-WMF5.1.ps1

• Unblock the Install-WMF5.1.ps1:

3. Check for current version of .NET Framework installed in Control Panel > Programs and Features:

• NOTE: .NET Framework 4.5.X version is the minimum requirement. If .NET 4.6 is installed, it is not necessary to uninstall. .NET 4.5 will not install if .NET 4.6 is already installed.

• Install the .NET Framework 4.5 exe file and reboot the machine after installation complete.
• Verify that the updated .NET Framework 4.5 installed via Control Panel > Programs and Features

4. Open PowerShell as an Administrator and check that the Execution Policy will allow scripts to be run.

• Get-ExecutionPolicy
• If it returns Restricted, then run:
  • Set-ExecutionPolicy RemoteSigned
• Check to find the current version of PowerShell installed:
  • $PSVersionTable

• Navigate to the folder of unzipped files (in this case it is the E:\Downloads folder):
  • Set-Location E:\Downloads
• Run the script:
  • .\InstallWmf5.1

• If the prerequisites are found, then the WMF5.1 upgrade installation will begin.

• Restart the machine at the end of the installation > Verify installation via Control Panel > Windows Updates > Update History

• Verify the successful WMF5.1 installation in an elevated PowerShell session:

2. Installation on WS2012R2 (and W8.1)

1. Have all current Windows updates installed on the WS2012R2 machine.

2. Download the WMF5.1 Package 

• Win8.1AndW2K12R2-KB3191564-x64.msu

3. Open PowerShell (PS) as an Administrator and check the current version of PS installed:

• $PSVersionTable

4. Double click on the MSU file downloaded and the installation process will begin:

4. Restart the machine > verify successful installation of WMF 5.1 via Control Panel > Programs and Features > Installed Updates:

• Verify the successful WMF5.1 installation in an elevated PowerShell session: