What I would like to do is create a clean virtual machine image as the output of a build of an application.
So a new virtual machine would be created (from a template is
Checkout Powershell Management library for Hyper-V on CodePlex. Some features:
Finding a VM
Connecting to a VM
Discovering and manipulating Machine states
Backing up, exporting and snapshotting VMs
Adding and removing VMs, configuring motherboard settings.
Manipulating Disk controllers, drives and disk images
Manipluating Network Interface Cards
Working with VHD files
You can actually script a fair number of tasks in MS Virtual Server:
http://www.microsoft.com/technet/scriptcenter/scripts/vs/default.mspx?mfr=true
http://msdn.microsoft.com/en-us/library/aa368876(VS.85).aspx
Also Virtual PC guy has got a ton of stuff on his blog about scripting Virtual Server/PC and now Hyper-V here:
http://blogs.msdn.com/virtual_pc_guy/default.aspx
VMware has similar capabilities:
http://www.vmware.com/support/developer/scripting-API/