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SAN FRANCISCO--If you're not running a peer-to-peer (P2P) application already, the chances are you will be soon, according to Bob Knighten, Intel's peer-to-peer evangelist.

When P2P comes up in conversation these days, it's usually referring to Napster. But P2P is about more than free music; it includes such applications as instant messaging and the SETI@home project, which uses idle computing resources in home PCs to search for intelligent extraterrestrial life.

"Peer-to-peer is something that's moving the focus of computing," Knighten said, speaking on the first day of a peer-to-peer conference put on here by the Digital Consulting Institute. "The variety of computers that become peer-to-peer clients is expanding."

Clients already taking part in P2P systems include PCs and PDAs (personal digital assistants), and the network is already moving toward the support of cell phones and fixed-line phones, according to Knighten.

P2P can be grouped broadly into three models, he says. They are "client-server computing," where the servers provide services and the clients request them; "pure peer-to-peer," which operates independently of central servers; and a hybrid model, where servers assist clients to find information stored on other clients. Most well-known peer-to-peer programs, including Napster and SETI@home, are hybrid types.

Distributed computing systems, which connect a large network of computers to create a single supercomputer, are used for everything from aerospace design to automobile crash test analysis, Knighten says. They are also used for analyzing sound patterns from outer space and working on the human genome project.

In fact, distributed computing is used for so many things that Intel decided it had to try something with it, too.

The company wanted to give employees access to training materials on demand, but there were logistical problems of doing so worldwide. Shipping out the material on CDs would prove too costly, and letting people download it on demand was too taxing on both Intel's WAN (wide area network) and on the nerves of users using dial-up modem connections.

So Intel did its best at merging the two models. When one user requests training materials--in the form of a video stream, for example--the materials are stored on his or her hard drive. When another user wants to view the same video stream, the network points that user to the first user's machine rather than back to the original source.

Already more than 200 companies offer peer-to-peer technologies of some form, and the technology has been around for a lot longer than Napster, Knighten says.

"Peer-to-peer computing was not invented a year ago," he says. "Some of the aspects have been around for 20 years or so. Others have been in development for three or four years."

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