Like "Internet", "Web", "Web 2.0", and now "Cloud", some words are used as a handle to grasp a lot of meaning very simply. That doesn't imply the information is simple. In fact, it is quite complex. But a communication shortcut can be very valuable when your time is finite. These words contain a broad spectrum of meaning. So depending on what portion of the spectrum you find interesting or want to promote, that is what the Cloud is - to you - and, therefore, others. That's why you get so many different definitions for these words.
Tune into the Cloud with your own peripheral vision and depth of view - and let me know what it means to you.
Here is one to kick it off - by SalesForce.