PowerShell is a free tool that lets application developers build cmdlets, or command-line tools, to automate common administration tasks.
PowerShell 1.0 Installation Package for Windows Vista includes 129 cmdlets for system administration tasks such as event logs, certificates, registry and using Windows Management Instrumentation (WMI), according to Microsoft. Custom cmdlets can also be developed using the tool. PowerShell includes support for Vista, XP, Windows Server 2003 and the next Windows Server code-named Longhorn.
The tool also has standard utilities for managing Windows in different data stores and formats including Active Directory, WMI, Component Object Model objects, Active X Data Objects, HTML and XML.
PowerShell can be downloaded from Microsoft's Download Center.