I think a pretty good definition of Cloud computing comes from Wikiepedia (http://en.wikipedia.org/wiki/Cloud_computing).
Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet.Users need not have knowledge of, expertise in, or control over the technology infrastructure in the "cloud" that supports them.
The above image is a diagram of cloud computing and some examples of sites the use this style of computing.
What is the most interesting part of this style of computing is that it takes a majority of what traditionally runs on a persons computer and places it on the internet. We no longer have to run the applications locally, we can use more robust servers to do the work for us and that frees up our machines from having to do so much. This can greatly reduce the cost of computers for people and eliminate a lot of the requirements people might have to have on there machine to run certain software.
There is a lot of potential in this. For example, there is a new service on the horizon called OnLive (http://www.onlive.com/). They offer an on demand video game service that allows you to play state of the art games on high end machines. They host all of the machines and equipment. All you need is a small console or computer to connect the their service and they stream the game to you. As games demand more computing power they upgrade their servers, you upgrade nothing. Its a very interesting concept. It eliminates the need for you to go to the store to buy games, or even have a physical medium to store the game.
Another example is the direction that all the cable, satellite and other television services are going with their dvr and on-demand technology. Dvr's originally allowed a viewer to escape the confines of normal tv programming by allowing the user to record tv shows anytime they wanted and access them later, all on a hard drive, all easy to use. On-demand takes this a step further. The on demand allows a user to just navigate to the program they want through and on screen menu and play it, with out having to record it. Networks on demand content is also growing such as CBS, NBC and Fox. A lot of movies can even be viewed on demand as well. Again, this eliminates the need for the user to download, or save content of their machine, or even have a physical medium to store the video on.
These are just a few examples of how cloud computing is affecting products such as gaming and television. The potential for educational use is even greater. Imagine a school being able to host the the software or content that there students need and then providing them with a low cost client terminal for them to access it. It could get more computers and technology into low income homes and improve education across the board. Again that is just one small example. I think the possibilities are endless! Here is the link to another blog by Thomas Bittman that talks about cloud computing in K-12 education (http://blogs.gartner.com/thomas_bittman/2008/11/26/cloud-computing-and-k-12-education/). His main points are low-cost and free technology, content growth and collaboration. It is an interesting read.
