Microsoft just opened the beta program for a new tool, the Offline Virtual Machine Servicing Tool, which aims addressing a concrete challenge: keep updated a large amount of virtual machines stored in a VM library and acting as templates for cloning operations.
Since these virtual machines are not supposed to be powered on the task is challenging.
To solve it, the new Microsoft tool uses PowerShell, System Center Virtual Machine Manager (SCVMM) 2007 and a patch management product between Windows Server Update Services (WSUS) 3.0 and System Center Configuration Manager (SCCM) 2007.
Thanks to PowerShell scripts, each VM is powered on by SCVMM and temporary deployed on a virtualization host available. At that point the patch management procedure is started and the VM is powered off as soon as it completes.
The last step implies moving the patched VM back to the Library.
This process is identical to the one performed by the new VMware Update Manager (VUM) included in VI 3.5.
Unfortunately, in both cases, there are major issues in case the administrator has applied the Sysprep to the VM: as soon as the virtual machine starts the Sysprep mini-setup starts as well, customizing the VM.
Enroll for the beta program here.