Looks like we've published a whitepaper on how Microsoft's own IT department uses Diskpart. Here's the summary:

The Microsoft IT group regularly uses the Diskpart.exe utility to dynamically increase disk volume capacity on servers running Microsoft® Windows Server™ 2003 and Microsoft Windows® 2000 Server. The Diskpart.exe utility is an integral component of the Microsoft IT “just in time” storage model because it extends disk volumes, without downtime or application interruption, thereby increasing availability and decreasing costs.

Enjoy!

--Jill