One of the problems with putting things into categories is that as technologies and the environment change over time, those which were once separate and distinct can become much less so. But, because we've grown so accustomed to thinking of them as independent entities, we can miss that shift.
From a practical business perspective, this can mean failing to notice that someone we never thought of as a competitor is now serving the needs of our customers. They may well be doing it in a different way or coming at a problem from a different mindset or design point. But, at the end of the day, they end up solving the same customer problems and taking away business. The datacenter space is replete with examples such as more distributed systems replacing centralized ones (through several cycles) and standard interconnects replacing proprietary ones.
Here's a new one to think about in the Web application and Cloud Computing space.
Is Web Hosting the same as Cloud Computing? It's tempting to say not. After all, isn't Cloud Computing the future while Web Hosting something that's been around since, well, the beginning of the Web (and even earlier if you consider all the various pre-Web Internet services)? But what is Web Hosting exactly? It's providing access over the network to a set of services--such as those associated with the LAMP stack--together with some storage capacity, and a bandwidth contract. For this reason, in Defining Cloud Computing, I wrote "we take a fairly broad view of Cloud Computing. It’s not just about the enterprise, just about the consumer, or just about delivering entire applications. Software as a Service (SaaS), Hardware as a Service (HaaS), Data as a Service (DaaS), and Web 2.0 are all part of the cloud. Even hosting providers are a sort of specialized, narrow case. We take such a broad view because all of these intersecting sub-categories do share at least one common characteristic: the Network is the abstraction layer. "
I bring this up because, as Netcraft writes:
With Amazon's recent offering of low-cost web application hosting, and now Google's free web application hosting, the conventional web hosting industry may be set to see some radical changes. With both services providing high scalability, yet without adding complexity, these could be seen as an attractive alternative to setting up a busy website on dedicated servers. Conversely, they are less likely to appeal to casual website owners, simply because the services require more knowledge and skill to use than simpler services such as Google Pages, Blogger or Apple iWeb.
There's nothing fundamentally different or special about Web Hosting. It's just a certain selection of network services and abstractions that hosting providers expose. As Netcraft suggests, it will probably continue to be a useful choice of services and abstractions for a basic Web site. However, newer approaches, whether Goggle's, Amazon's, or from a lesser-known company like Mosso, may well become the favored approach as environments get more complicated and capacity needs more variable.