The way that "cloud computing" is marketed makes me expect a pitch for deed to a bridge in New Jersey will come next.
In a sentence, cloud computing is when data, services, and apps that run on one of your computing devices are available on all of your devices because they run somewhere else. That somewhere is called the cloud because it makes your stuff available everywhere.
The problem is that it kinda feels like nowhere, doesn't it?
There's no business behind the cloud, per se: nobody has trademarked it, to my knowledge, and it hasn't been productized with a capital "C." You can't buy The Cloud, so it's not like its marketing is bad. It's an idea, or a model (or, God forbid, a paradigm), and it gets defined differently by the promoters, critics, and circumstances in which it gets used.
So the cloud is a good thing when Apple helps me automatically sync my contacts files across my desktop, laptop, and iPhone. It's a bad thing when it comes to Oracle's purchase of Sun, because owning hardware might not fit into the, er, cloudy future. The cloud is good for Google, not so good for Microsoft, and sort of good or bad for system security, depending on who is doing the clouding.
It's the technology corollary of beer's drinkability. The cloud is a brand attribute that has no set meaning, which means that it risks becoming meaningless.
I'd offer that the word "cloud" is just a poor choice for a paradigm label. Clouds are fluffy, insubstantial, and sometimes filled with precipitation. They wander the sky with no apparent direction or purpose. In everyday usage, water that's cloudy isn't a good thing to chug; perspectives that are clouded aren't particularly accurate.
Maybe it's like the old term virtual reality; remember how VR was going to transform everything, from database design to shopping? We never really agreed on what it meant, but it sure sounded cool (and inspired some wild yet marvelously dated sci-fi movies, like "Lawnmower Man"). We sort of have it now, via the virtualized, real experiences enabled by IM, or the ways information architectures have gotten more user-friendly, but it doesn't look anything like what any of us imagined VR would look like.
I think the cloud is destined for the same fate. It'll get replaced by services like ubiquitous communities, data integrated with real-time experience (now called augmented reality, which is another cool, silly term), smart products, etc. We'll laugh about the old days, and hatch new terms to use.
But for now, I'd be leery of any business that uses references to the cloud in their branding. There just may be no there there.