The good is the enemy of the best here. With few exceptions, good sites deliver most their value without resorting to push techniques.

Suppose YC hacker news incorporated some kind of "push" system. Unless it was very unobtrusive I probably would try and turn it off since I want things to stay static while I'm reading.

I could imagine this being useful to complement a management interface, especially for providing detailed progress indicators.

Is Virtualmin ( http://www.virtualmin.com/ ) doing anything with Comet?