Ah well, never mind, iTTv2 (coded in Silverlight) never really managed it either, although iTT1 (coded in C#) did.
Here's some food for thought that might be more do-able. I know at the moment everyone has to be in the same "room" (i.e. looking at the same map or graphic or whatever). However, it has been mentioned that it might be A Good Thing to allow different players to be in different rooms. If this happened, would it be possible to have a game setting that selects whether you can hear people whatever "room" they are in, or can only hear people in the "same" room as then.
If that's no do-able either, well, we can live with text whispers for sure.
Thanks,
Mr G.