VMware has released VI Toolkit 1.5. They have added 32 new cmdlets, enhanced their existing cmdlets, and fixed tons of bugs. VI Toolkit (for Windows) is a command-line and scripting tool built on Windows PowerShell, and provides more than 150 cmdlets for managing and automating your VMware Infrastructure.

VI Toolkit (for Windows) 1.5 Beta supports the following VMware environments:
VMware ESX 3.5
VMware ESX 3i
VMware VirtualCenter 2.5
VMware ESX 3.0/VirtualCenter 2.0

You can download the software here: http://www.vmware.com/sdk/vitk_win/index.html

The release notes are here: http://www.vmware.com/support/developer/windowstoolkit/wintk15/windowstoolkit15-200901-releasenotes.html