I had the chance to take part of a multi people conversation on Google Wave.
Overall, I have to say that it was an interesting chat experience, but it lacks some very important things. Chief among them, if you are going to allow multiple people to edit at the same time and expect to give a real time experience, you have to provide good experience when people are editing “beyond the fold” (the areas of the documents that I am not currently viewing.
Replaying stuff is nice, but it isn’t working for the real time edit portion, which is the most interesting bit.
Overall, I have to say that I found it to be somewhat like IRC, and I dropped out of that years ago, because it had a real time requirements that I could not justify. I much rather use something that is by nature async, with a sync-like experience, like email or twitter.