Phases of the Sun
A search engine, for example, can't take advantage of Sun's network.com service to process large amount of data, since the FAQ says: "Please note that any time your storage usage exceeds 10 GB, your job will be terminated until you comply with the 10 GB storage limit." Most likely, the PC that you use to read this post offers ten times more space than Sun's Grid: clearly, network.com is not a supercomputer for at least one dimension of "super."
Yet for certain applications, Sun's service is a good fit. If you want to render high-quality 3D animations from your basement, now you can do it with minimal startup cost. Sun's Grid and Amazon S3 suggest that both the hardware and software for the world computer is being actively developed. Sun and Amazon are not just showcasing technology, but pioneering the way to the "pay-per-use" business models of the future.