We are working to get offical public documentation on this subject, I will update this post once we get a KB published...
When writing .NET code which uses the System.Management.Automation namespace or using Windows Powershell you may receive the following error when you attempt to load the Exchange Management Shell snap-in.
"No Windows PowerShell Snap-ins are available for version 1"
Exchange 2007 is only supported on 64-bit Windows and is, itself, a 64-bit application, therefore many of the components including the shell extensions are 64-bit.
On a 64 bit version of Windows with Powershell installed there are two versions of Powershell.exe. One is the 32-bit version (found at C:\WINNT\syswow64\windowspowershell\v1.0\powershell.exe) and the other is the 64-bit version (found at C:\WINNT\system32\windowspowershell\v1.0\powershell.exe). The Exchange Management Shell snap-in will only load into the 64-bit Powershell. If you try to load it into the 32-bit Powershell.exe, you get the error message above.
Likewise, if you are automating Powershell from an application it must be compiled for 64-bit in order to load the Exchange Management Shell snap-in.