Frank Koch from Microsoft has published two free ebooks giving you a quick introduction to PowerShell.
Book 1: "An introduction to scripting technologies for people with no real background knowledge"
Book 2: "Administrative tasks using Windows PowerShell"
Get your English copies here:
http://download.microsoft.com/download/4/7/1/47104ec6-410d-4492-890b-2a34900c9df2/Workshops-EN.zip
Both books were originally written in German. You can still get the German versions, too:
http://download.microsoft.com/download/4/7/1/47104ec6-410d-4492-890b-2a34900c9df2/Workshops-DE.zip