AlwaysOn has an interesting interview with Bill Joy, who co-founded Sun Microsystems back in the day and is currently with famous VC firm Kleiner Perkins. Joy's had a theory for a while now about there being six Webs. In this article he expands on that and moreover says it was a key driver for Sun's Java strategy in the 90's.
"We identified six webs. Those first four—here, near, far, and weird—are distinguished by their human interface. Then we said there are clearly two more that are essentially invisible: machine to machine and server to server. That is what became known as enterprise computing. The realm of Enterprise JavaBeans and .NET and all that for businesses to remove friction from the global economy by using weblike and Internet-based things to connect things.
We call that a kind of P to P, because it was peer to peer; basically my business computer can talk to yours. And opposite intermediaries can emerge. The last one was D to D for device to device, which would be the whole realm of embedded systems and the Net as a universe of devices and sensors connected by UWB and 802.15. These things have come along since then. But the world is an embedded sensor net. All six of these webs essentially become interconnected pools of information that can be hyperlinked, but they are mostly "internetted" and have very different business characteristics. So we had this model, this roadmap, for how we thought this was going to develop a dozen years ago, and we used it to drive the Java strategy."