Clouds form known patterns of shape, consistency and color. These patterns have formal names too: cumulus, stratus, nimbus, etc. But there are also the patterns that are only in the eyes of the imaginative: a dragon, or a face, or Aunt Betty being chased by a fire-breathing turtle.
Cloud computing implementations are composed of common elements such as network servers, enterprise software, routers, etc. There will be common configurations, however, the power of the cloud comes from the idea that capacity, software, storage, etc. are delivered on demand as a service. So despite the fixed configuration that is really the connected inventory, the shapes of clouds are indeed malleable. So what shapes will we see in these clouds?
One of the most widely used examples of a cloud benefit is the greeting card company that has flat business through the year except for specific holiday peaks. The cloud allows that company to expand their capacity for those peaks only, saving them money. In this example, the cloud is hosted by a third party provider.
But what about that nebulous provider? Such a company will still have to manage capacity and other IT services for all its customers. It has the same issues that any IT shop would have. Finite resources that have to handle all the demand. The cloud principle allows it to provision resource as it is needed, but then this provider will only be able to handle so many customers that have peak business around the various holidays other wise there is no gain. In fact I think that these providers will have to plan which kinds of business they can host to maximize their 'face' time.