A basic chat room in php or asp is quite simple, about a hundred lines of code and can be found on the net for free e.g. www.asp101.com

Adding flash output would be achievable using the xml feature in V4 and all that would be required is a reload of the page every 5 or ten seconds. Q: for Bret, can a php server perform streaming xml yet?

The real question is what would you want to do? Currently there are chat rooms using java applets which "animate" the icons for each visitor. This would be a natural candidate for a series of sequences of animation e.g. LOL and ROFL in chat speak could translate to the animated character actually rolling around on the floor laughing.

Since the text strings would be in the xml data stream too, the text could be animated with a set of preset tags e.g <SERIOUS>,<SEXY> etc

e.g. <Dave> <SERIOUS> Do you mean that? </SERIOUS></Dave>
<Mary> <ROLF> Yes Hee Hee </ROLF> </Mary>

So - what conceptually do you want the flash portion to do over and above the normal chat room operation.?