If you are into printed books there are a couple of really good Powershell books that you should check out.

O"Reilly has a great book simply titled Monad.  This book was originally written on one of the beta versions of Powershell but if you purchase the book you can get the updated version at no charge.  Check out the book here: http://www.oreilly.com/catalog/powershell/

Jeffrey Hicks and Don Jones are also writing abook titled Powershell from Sapien Press.  It looks good so far.  I can't wait until it releases!  Check it out here: http://www.sapienpress.com/