I try to learn something new everyday, and this would fall under that category. I was not aware of any scripting or COM interfaces built into the Group Policy Management Console.
Wrong! There are even some sample scripts posted on Microsoft's download center.
The description of the sample scripts: The Group Policy Management Console (GPMC) provides a comprehensive set of COM interfaces that you can use to script many of the operations supported by the console. Included in this download is a set of sample scripts that make use of these interfaces.
It looks like these are primarily for Windows Vista and Windows Server 2008.