The following is an excerpt from an article published in the October 25th edition of The Economist:
The importance of this shift from a monolithic [software] product to [software as a service] is hard to overstate. In a sense, it has seeded the cloud, allowing the droplets - the services that make up the electronic vapour - to form. It will allow computing to expand in all directions and serve ever more users. The new architecture also helps the less technically minded to shape their own clouds ....
Just as for the industrialisation of data centres, there is a historic precedent for this shift in architecture: the invention of movable type in the 15th century. At the time, printing itself was not a new idea. But it was Gutenberg and his collaborators who thought up the technologies needed to make printing available on a mass scale, creating letters made of metal that could be quickly assembled and re-used.
For the complete article, go to Creating the cumulus: Software will be transformed into a combination of services.