Update 9/19/13: A side-by-side coexistence of PowerShell 3.0 and PowerShell 2.0 is supported starting with Exchange 2010 SP3. Note that Exchange 2010 will only use PowerShell 2.0 so PowerShell 2.0 ...
Updated Jul 01, 2019
Version 2.0
Blog Post
Really disappointed that MSFT did not properly regression test the Framework prior to deployment. Exchange 2010 is not a fringe product. Customers should not have to deal with mopping up due to bad planning and testing on MSFT's part. In addition to a pre-deployment heads-up regarding the compatibility issues, Windows Update should have been configured to not suggest the Framework if a conflicting product was installed on the target computer. Not good. Very disappointed. I am venting here; however I am not faulting the Exchange team on this ... if anything, thanks go to them for the notification ... it is just that others should have been more careful and responsible.