- KB2506143 is the WMF 3.0 update for Windows Server 2008 R2 SP1 and Windows 7 SP1;
- KB2506146 is the WMF 3.0 update for Windows Server 2008 SP2.
These updates will install Windows Management Framework 3.0 which includes PowerShell 3.0. However, Exchange 2007 nor Exchange 2010 currently works with PowerShell 3.0 and installing these updates will render your system unusable, including workstations from where you run the Exchange Management Tools.
The related updates have been published recently as optional updates through Windows Update. However, depending on your patch management methodology (e.g. WSUS), these updates might be installed automatically (e.g. accept all).
Therefor, it is advised to block these updates from being installed on your Exchange 2007 or Exchange 2010 systems when possible; Exchange 2013 requires WMF 3.0 therefor this doesn’t apply to systems running Exchange 2013.
Note that PowerShell 3.0 compatibility is announced for Exchange 2010 SP3, which is scheduled for Q1 2013; compatibility with Exchange 2007 isn’t announced nor expected.
Credits to Exchange fellow Michael B. Smith for discovering this.
Update, December 14th, 2012: Microsoft has acknowledged the problem here.
Update, December 19th, 2012: Microsoft pulled the updates from Microsoft Update / WSUS. Note that Exchange wasn’t the only product affected; WMF 3.0 also breaks Sharepoint 2010 for instance. Needless to say, WMF 3.0 should also not be installed on systems containing Small Business Server.