Comet

Comet is cool too.
There may be better more professional words for it. I think comet is the best one because it gives it a name and lets us know that it has to do with Ajax.

The idea behind comet is reverse Ajax. Letting the server communicate with the client.
A sort of way to look at it is in Ajax the client initiates the the communication when it wants something. In Comet, the server initiates the communication.