My co-author Janique Carbone has posted two new bonus scripts on her site http://vscommunity.com.
Both scripts have to do with finding out information about differencing disks.
GETVHDParentInfo - Allows you to specify a VHD file on the command line and the script will tell you if the VHD is a differencing disk and then walk the tree of dependencies to show you the entire hierarchy of the parent child relationship
ListDiffDisks - Allows you to point at a Virtual Server host and it will enumerate all the virtual machines and all of their VHDs, telling you which ones are differencing disks and also printing the entire hierarchy of the parent child relationship.
These are posted in the Downloads area and require you to be a registered user of the site to download them.