Windows PowerShell 1.0 (previously code named Monad) has been released to the Web. This is a very powerful command line/scripting environment for Windows XP SP2, Windows Server 2003, Windows Vista and Longhorn Server. Exchange 2007 will also base its command line and  scripting interface on Windows PowerShell.  Have a look at the Scripting with Windows PowerShell page on the TechNet site for lots of information including some great introductory webcasts. There is also a repository of scripts ready for you to use.

Update: If you want to see some of the power (ahem) of PowerShell then have a look at this video on Channel 9.