The Schweizer IT Professional and TechNet Blog is sharing a free Windows PowerShell course book that they’ve translated to English. The book seems to be pretty good.
From their blog entry:
Due to its great popularity, we have decided to translate the Windows PowerShell course book to English. So if your mother tongue is not German, maybe you are interested in the English version instead. The book gives you a short introduction with many exercises about the interactive part of Windows PowerShell as well as some hints how to use other objects like WMI, .NET or COM objects like Excel or Internet Explorer.