It's not widely used. Yet. They were selling invitations when it first
came out because everyone wanted to get in on the next BIG thing.They
are pretty plentiful now though.
I have invitations left too. If you send me an email address Curt, I
can send you an invite.
It is in preview though. I tried to go from Wave to Google groups
yesterday and it got stuck in some loop that I had to close the window
to stop. Not a biggie, but not mainstream either.
Bob