"The Cloud" is often confused with the Internet, probably because the Internet is officially portrayed as a cloud in diagrams. A cloud is in fact an application or suite that runs on a server and is served to thin clients, traditionally through a browser but not exclusively. The Internet is a great facilitator to such a deployment. Pretty much all processing and data storage is kept on the server and the user merely taps into it remotely.
Obvious advantages of cloud solutions are centralised deployment and maintenance and also the ability to access applications from almost any device that can run a browser. There is also the major advantage of mobility, allowing users the freedom to work from anywhere with a connection. In recent years we have had major strides in mobile technology like netbooks and 3G as well as rapid price reduction for said hardware and services, pushing the mobility envelope even further.
The desktop remains a tool for the professional but with the creation of netbooks and smartbooks we no longer need the teraflops of processing power we have today. While the SETI project might not like this, it means that the common household will consist of a netbook per family member and one home server to store data, run high end games, run professional applications, run the home theatre and eventually manage the automated home of the future.
Another big advantage of using the cloud is collaborative interaction, or as it's commonly known; social networking. Facebook for instance has cultivated a fantastic concept and put it to bad use. While we all like the idea of playing together, the truth is we're so caught up with 'doing it together' that we don't really care that what we're doing is wasting time. But wait, here comes Google and says let's take the old form of internet collaboration (email) and throw in the new form of internet collaboration (social networking) and out pops Google Wave. And while we're at it, we'll do away with this turn based approach and make it real time. We now have the boardroom of the future and guess what; it's free, as with all Google's best offerings.
So we have everything plus our boardroom meetings and presentations in the cloud, why the hell are we still sitting in traffic all year round. We might as well be sitting on a beach, working in comfort. Hold on for a second, my company has slightly more involved requirements, Google does offer all the basics but they just don't cut it with what we need to do. Enter Canonical and their open source Ubuntu Enterprise Cloud. UEC is basically a DIY cloud infrastructure and is currently the only private cloud infrastructure available as far as i know. Just get in some development consultants and build your own customised (cloud based) business application and host it locally.
We now have major cost savings in workstation budget because all your employees are using cheap netbooks instead of powerful desktops and/or notebooks. We also have the huge cost savings of not having to buy software, however both Google and Canonical offer some advanced paid for services if needed. And of course, if all your employees are sitting on a beach somewhere you need not pay for that elaborate corporate office space ;)