Software-as-a-Service is the ultimate in virtualisation
I was attending a seminar today alongside a virtualisation vendor and it struck me that Software-as-a-Service is the ultimate in virtualisation.
Traditional virtualisation turns hardware into software, but Software-as-a-Service turns software into a commodity. Virtualisation software removes the complexity of managing multiple hardware platform with the complexity of installing a hypervisor shim on, albeit a less number of, platforms and shuffling around virtual machines around the infrastructure. IT staff still have to maintain hardware, they still have to manage and patch the operating systems and applications installed on the virtual machines - and now they have to manage the virtual machine layer as well.
Software-as-a-Service removes all of the hardware and software on premise, replacing it with a business focused service rather than a set of technical components that you have to manage.
In other words, virtualisation turns hardware into software - Software-as-a-service turns software into a utility.