http://infobank.com.au/showntell/
Feel free to drop by and checkout this working example of a realtime collaboration application that runs in Flash 5 or better (e.g. over 90% of browsers). The server side is based on SAX XML pipelines and the client/server interaction is based on a persistent bi-directional XML connection.

NOTE: Most of this framework will soon be released under GPL as an Open Source project.