Tim O'Reilly has an interesting post about dial tone. Yeah, I know, it doesn't sound that interesting, but it is one of those things like Web 2.0 and Ajax - a new word that describes an old idea:

Dial tone is a fabulous metaphor for one of the key principles of Web 2.0, which I've called "the architecture of participation," but which might also simply be described as the design of systems that leverage customer self-service.

One thing I've found interesting about these types of metaphors (buzzwords?) is the contempt that many people have for them. How many Ajax developers actually like to use the word Ajax? In one of Terry's talks, he describes Ajax as a design pattern, which I think is a pretty good description. Most people I know can appreciate design patterns - by applying new names to old ideas, we can better categorize our solutions to common problems. This has a number of advantages, including the fact that it gives us a common vocabulary to describe abstract ideas. For some reason, however, these same people despise Ajax.

Tim is adept at identifying social design patterns - ideas like Web 2.0, where many people are thinking the same thing, but no one can describe it clearly and succinctly. Labels like Web 2.0 are catalysts for discussion and the spread of knowledge. Good ones stick. Bad ones don't.

I'm not sure whether dial tone is a good metaphor or not, but it makes a lot of sense in context:

You can regard the history of the computer industry as pushing "dial tone" further and further up the stack.

This is almost exactly how David described Ning during his interview on the Pro-PHP Podcast.