Powerfull stuff, this PowerShell.

 

10 reasons why you should learn to use PowerShell

 

http://www.microsoft.com/PowerShell - Microsoft (main?) site on PowerShell

 

PowerShell features - various systems PowerShell can work on.

 

Wikipedia - gives a good overview,
it also shows which applications are supported by PowerShell.

 

There is a comparison of Command Shells on Wikipedia.