[svas]

Even in the AJAX timeframe, there was still a way to do async push style interaction from server to client. See Comet: http://en.wikipedia.org/wiki/Comet_%28programming%29

Gmail used this technique via a hidden iframe.

[saurik]

Yeah; I had done this sort of stuff in 1998 using a custom HTTP server I wrote in VBScript.

[est]

On IE they used ActiveXObject called "htmlfile"