Defining Cloud Computing

Cloud Computing views the whole group of machines as a single computational machine. It splits up work symmetrically and asymmetrically to the group. Often, cloud computing uses address space to perform computation, e.g. Google's Map-Reduce would use address space to help sort. This leverages the best hardware (routers) to do the information routing. It leaves the hardware optimized for storage (local hard disks).

In Cloud Computing, configuration is significant. You array the machines in a replacable manner. But the arrays are setup for speed, storage, and networking.

This could be a renaming and elaboration on grid computing which views computational cycles as a resource much like the electrical grid. Grid computing sells the grid resources. It doesn't configure the networking. Some grids like Seti@Home have significant network constraints which make it impossible to use for all but the smallest Map-Reduce problems. Cloud computing is free of the constraints of Seti@Home's node's bandwidth limitations.