This post is disingenuous. In particular:

  [Cloud Operating Systems] enable the vision of light and fast application servers, while preserving the superior security and flexibility of true hypervisors.

Hypervisors are only secure if you don't need any sharing. If you have two applications running as separate guests and they need to exchange data, then all of the security issues that you'd have on a normal OS return, but they are harder to solve, because the Hypervisor doesn't provide much support!

As an extreme case, consider running all of your applications on your Desktop in their own VM. Now, you are in your web browser and you download a Word document that you want to edit. Somehow, you have to transfer this document to the Word Processor VM to edit it (they have different file systems so you need to use something like scp). If, after you're done editing it, you need to send it to someone via email, then you'll have to copy it to the Email VM. It's not how to see how this seriously impacts usability!

When sharing is required, then a Hypervisor is not helpful. That's not to say that Hypervisors are useless, as the author claims his opponents say. Hypervisors are good for running different operating systems on the same hardware and they are good at isolating the different OSes from each other. However, once any sharing is required, hypervisors are not the right tools for the job.