[Shish2k]

> send every message to every client in the world

That's what I do, as I can't think of any alternative that is equally analysis-resistant

> A few thousand bytes a second is an awful lot of text

I was planning for ~500 bytes / sec so that traffic spikes wouldn't block up the send queue, but now that I think about it you're probably right -- even at 50 bytes/sec, the network speed cap would still be a fairly small factor compared to the amount of time spent typing...