See below for sections on Commercial training, free online traning and books.

Commercial training

Microsoft: Automating Windows Server 2008 Administration with Windows PowerShell
Course 6434: Three days; Instructor-Led
http://www.microsoft.com/learning/en/us/syllabi/6434afinal.mspx

Microsoft: Windows PowerShell for Administrators
Course 50025A: Three days; Instructor-Led
http://www.microsoft.com/learning/en/us/syllabi/50025afinal.mspx

SAPIEN: Self-paced Training, Online Training, Classroom Training, and Private On-site Training
http://www.scriptinganswers.com/Training.asp

CBT Nuggets: On The Job Training Series: Windows PowerShell
http://www.cbtnuggets.com/webapp/product?id=456

K Alliance: Windows PowerShell Training Courses
http://www.kalliance.com/microsoft-it/windows-powershell.htm

The SANS Institute PowerShell Training COurse
http://www.windowspowershelltraining.com/

Winstructor: Windows PowerShell Training
http://www.winstructor.com/products/Windows-PowerShell-Training.html

QA: PowerShell Training Courses (UK)
http://www.qa.com/training-courses/technical-training/microsoft/scripting/powershell

Verhoef Training: Windows PowerShell (UK)
http://www.verhoef-training.co.uk/outlines/WNPS.htm

TrainSiganl: Exchange Server 2007 PowerShell Course Outline
http://www.trainsignal.com/product_master_page_exchange_server_2007_powershell.aspx?ProductId=36

KOENIG: PowerShell for Windows Server 2008
http://www.koenig-solutions.com/training/Powershell_admin2008.asp?gclid=COy62pzC6JoCFQQ9ZgodHzZ2CA

Free online training

-ExclusivelyExchange provides excellent free online resources for learning more about PowerShell and Exchange.

Books

-Coming soon!

Thanks to Shay Levy, Aleksandar Nikolic and Max Trinidad for helping put this list together.