Windows Powershell is something I've been meaning to learn for quite some time. It started out as the Monad Project at Microsoft and I remember seeing it discussed at Code Camps but never spending the time to go. I thought it was just another command.com with special commands.
Turns out, I was very wrong. As far as I'm concerned, it's strength is that you can reference .net assemblies directly. That means, you can access everything in .Net just like a first class language. Be that C# or VB, you can get to all of it. You can write your own assemblies and reference them as well! It of course if fully object oriented, very rich, and full error handling. Very cool
So, back to the book. Bruce Payett does a great job of introducing Windows Power Shell (aka Monad) and taking you step by step through the process of using it. He has lots of great examples and the book, as you would expect from a Manning book, is well indexed and well illustrated. I highly recommend getting it if you have not used Power Shell before.
Windows PowerShell in Action