SynJunkie has written a nice, detailed post that shows some of the administrative tasks that can be performed with Powershell. He shows how to perform many different system administration functions, from editing the registry to filtering event logs.
If you’ve never used Powershell before, I’d recommend you check it out. It’s a free download from Microsoft, and is available for Windows XP and Windows Vista, Windows Vista x64, Windows Server 2003, and Windows Server 2003 x64. Powershell is built into Windows Server 2008.
You can also download the Windows PowerShell 1.0 Documentation Pack. The Documentation Pack includes the Windows PowerShell Getting Started Guide, the Windows PowerShell Primer, the Windows PowerShell Language Quick Reference, and Windows PowerShell V1.0 Release Notes.
The Windows PowerShell Quick Reference, which is a quick reference guide to commonly-used Windows PowerShell commands, is also available as a separate download. You can also get the Windows PowerShell Graphical Help File, which is the Windows PowerShell help in graphical help format (.chm file).
Lastly, Frank Koch has written two Powershell books that are available as a free download. The first one is subtitled “An introduction to scripting technologies for people with no real background knowledge”, and is available here. The second book focuses on server administration, and can be found here.