The Economist has a nice special report on Cloud Computing and corporate IT, and successfully explains the various flavors, from the SaaS/Gmail to the VDC-OS enterprise cloud. It’s hard to pull out one quote, so here are two samples:

The evolution of data centres | Where the cloud meets the ground | The Economist.

a way, we’re cleaning up Microsoft’s sins,” says Paul Maritz, VMware’s
boss and a Microsoft veteran, “and in doing so we’re separating the
computing workload from the hardware.” Once computers have become more
or less disembodied, all sorts of possibilities open up. Virtual
machines can be fired up in minutes. They can be moved around while
running, perhaps to concentrate them on one server to save energy. They
can have an identical twin which takes over should the original fail.
And they can be sold prepackaged as “virtual appliances”.

The economics of the cloud | Highs and lows | The Economist.

Cloud computing is unlikely to bring about quite such a dramatic
shift. In essence, what it does is take the idea of distributed
computing a step farther. Still, it will add a couple of layers to the
IT stack. One is made up of the cloud providers, such as Amazon and
Google. The other is software that helps firms to turn their IT
infrastructure into their own cloud, known as a “virtual operating
system for data centres”.

Drawing a neat diagram of the IT stack will also become increasingly
difficult because the layers are becoming less distinct. In a world of
services it often does not make sense to think of hardware and software
separately, argues Padmasree Warrior, the chief technology officer of
Cisco. Both need to be blended to offer new services, she says.

Here are the articles in the series: