Microsoft has released the Windows Management Framework (WMF) 5.1, including Windows PowerShell 5.1, to the web. You can download it here. This is the final version that released with Windows Server 2016, though it doesn't include all the features of PowerShell 5.1 that are on Server 2016 because some are not supported on earlier versions of Windows. WMF 5.1 is available for Windows Server 2012 R2, Windows Server 2012, Windows 2008 R2 SP1, Windows 8.1, and Windows 7 SP1. (Note, this does NOT include Windows 8.0!)
Installation on Windows 7 and Windows Server 2008 R2 has updated installation requirements. Please carefully read the Release Notes before installing.
All that being said, I'm updating all my computers to the latest version. My Windows 10 and Server 2016 computers are already at the WMF 5.1 level, of course, but I still have some legacy servers that need updates. They'll be getting them over the next couple of weeks, and my lab image templates are getting updates as well.
There are some older applications that require earlier versions of .NET than the version included and enabled by default on Windows 8 and Windows 8.1. Normally you can enable the .NET Framework 3.5 (which includes .NET 2.0 and .NET 3.0) as a Windows Feature. (Control Panel, Programs and Features, Turn Windows Features on or off.) But in some environments, especially those using SBS and WSUS, you may get an error message:
0x800f0906: “Windows couldn't connect to the Internet to download necessary files. Make sure that you're connected to the Internet, and click Retry to try again.”
This, of course, is totally bogus because the computer IS connected to the Internet, but save yourself some grief and do it from the command line in the first place. The files you need are part of the DVD (or USB stick or whatever) that you used to install Windows. Just insert that media and from an elevated command or PowerShell prompt type:
PSH> DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:E:\Sources\SxS
Deployment Image Servicing and Management tool
Image Version: 6.3.9600.16384
The operation completed successfully.
Where the E: drive in E:\Sources\SxS is replaced by the drive letter of the DVD, USB or other media source or your Windows distribution media. Or, the pure PowerShell way:
PSH> Enable-WindowsOptionalFeature -Online -FeatureName "NetFx3" -All -LimitAccess -Source "E:\Sources\SxS"
Now, whatever application it is that needs this older version of the .NET Framework will be happy. (Zune 4.8, in my case.)
Updated: 13 November 2013: Added PSH equivalent.
: 2 June, 2014: Fixed curly quotes
: 13 October, 2014: Confirmed, the same command works in Windows 10 Preview
Microsoft has released an update rollup to WMS. This update rollup replaces UR1, which had an installation order problem when installed on an SBS Essentials network (or with Windows Storage Server 2008 R2 Essentials). The details of the update are covered in MS KnowledgeBase article 2626067. UR1.1 is cumulative, so you can install it over the top of UR1 if you already have that installed, or you can install it on a plain RTM system. It will supersede UR1 on WU/MU/WSUS.
(note: if you already have problems because of installing the existing UR1, you need to re-install the SBS Essentials to correct the issue -- just connect to http://sbseservername/connect and re-install.)
Before you can install Windows Server 2008 R2 SP1 (or Windows 7 SP1), you need to uninstall the beta or RC version that might be installed. On a GUI install of Windows Server, no problem, run AppWiz.cpl and click on Updates. But on Hyper-V Server 2008 R2 (or Server Core) there is no obvious way to uninstall the beta or RC versions of the Service Pack. You need to use the command line version of the Windows Update Installer: wusa.exe.
wusa.exe /uninstall /kb:976932
It’ll take a couple of reboots before it’s completely uninstalled, and then you can install the SP1 you just downloaded.
Update: Note, if it wasn't clear. This command line works equally well from GUI installs, including Windows 7.