I finally got invited to Google Wave. As a potential GW developer, my interest has waned, but I did login to check it out.
My first impression was that the interface didn't look so good on my machine. It looked a lot like a clunky GMail. Also, I really don't like that GMail has instant messenger / chat. Maybe some people do, but I really don't - I never feel like I can fully turn it off. When I noticed something similar was "on" in Google Wave, I lost a lot of interest. I do have to ask the question why Microsoft, and now Google, are working so hard to change email as we know it?
I'm sure my curiosity will recover and I'll look into Wave again, but for now, NGINX as a "Comet" server sounds more interesting to me.