I disagree: just like Ajax, Comet is a very necessary buzzword. The technology behind Comet existed for years before the term "Comet" was coined, but very few developers were aware of it because there wasn't a good term for it. The same is true of Ajax. In fact, Comet was coined precisely because the term "Ajax" had had such a large influence on adoption of the underlying technology.
You don't need to give everything a label, one reason I don't like design patterns.
The idea behind Comet is an astoundingly simple one. It's using as many techniques as you can think of to emulate a continuous connection from client to server. That's it.
If developers can't "invent" it themselves, they aren't a very good developer. Giving them a ready made buzzword won't fix that :)
If it was an astoundingly clever algorithm, sure give it a name. But put 10 good hackers in a room that have never heard of or used comet before, and ask them to make a responsive app with javascript, I bet all 10 will 'invent' comet.
Vocabulary is important.