Cloud hosting is good, if you need it.

Savvis are in the top right of the Gartner Magic quadrant for cloud privisioning and services, their site has some good explanation for what the industry leaders consider cloud.

http://cloud.savvis.com/

I use a cloud system to provision servers so that I can install known configurations of server on different types of hardware without issue.

So for Joe Bloggs's wordpress site, cloud is not really necessary, but for a popular website who have to provision more and more servers every day of a known quality, regardless of the hardware they are running on this is a fast and easy way to do so.