Offline virtual machines are a big security headache for organizations. Because virtually all security patching and updating tools assume (and require) that machines are turned on for them to successfully do their work, your libraries of virtual machine templates aren't getting updated as they should.

Today I was poking around Microsoft beta site and discovered that they are working on an Offline Virtual Machine Servicing Tool. The product is yet in beta, and I don't know much more than its name and what I assume it intends to do. But its worth mentioning here, because this problem is a stealth killer in pretty much all organizations that use virtual machines to any extend.

You can sign up for the demo program at this site. If you're using virtual machines at all, consider keeping up on this topic, because the security of your powered off VMs can come to bite you at some point in the future.