Vivek had originally posted about how to do some basic Exchange cmdlet access from C# -- several months before E2k7 released: Calling Exchange Cmdlets from .Net Code. However, by the time we released, some things had changed in the technique and Vivek's examples were out of date.
Recently, someone pointed me to the updated UE docs that explain how to do this sort of process: Using Exchange Management Shell Commands With Managed Code. Good stuff, everyone likes UE documentation that's officially out on Technet.
But then, best of all, the other day Nick posted his analysis of doing recipient management wrappers in C#: Managing Exchange 2007 Recipients with C#. This post is a great roll-up of all the stuff you need to know to get this working properly with Exchange 2007 RTM and a bunch of usage examples. Sweet!