When you say "incremental updates", does each refresh contain all the preceeding information?

From what the poster said, I think there's no refreshing of the page at all.
I think the server is just printing stuff and the browser renders what it cans before the whole page is done downloading. This works kind of well is some scenarios and even better if you turn on autoflush on the server side.

However there are some catches. E.g. AFAIK, IE will only render a table after it gets the closing tag. And possibly some more of these kind of glitches.