Wave from what I read was developed for use internally at Google when Gmail was insufficient. I'd be curious to see what's being used within Google right now in the collaboration space. People who were once using wave, what are they now using?
Up until the day I left Google (last Friday), my team was still using Wave. We were a bunch of ex-Wavers though, so we were more likely than others to still be holding on.
I should point out that our internal version of Wave was different from the external version in at least one very important way: when a wave was shared with a group that you were a member of, the wave was sent to your inbox. Externally, you would have to set up a search to find that wave, so basically nobody ever read group waves. The idea behind the decision was to reduce inbox noise (particularly important in beginning few months), but that also meant reducing utility for group collaboration.
We were close to releasing proper groups support in the external version, so you could easily choose which groups to follow/unfollow inside your Wave inbox, but were discontinued before that made it out.
So, Wave was awesome for group collaboration, but unfortunately, we never gave the external world much of a real opportunity to witness that.
(And yes, there were other issues with Wave. Just thought I'd point out that one.)
That makes a lot of sense. My campus ACM group used Wave an enormous amount when the beta invites started going out, and we kept two organizational waves which mimicked the system you describe. One was a list of the screen names of every member, and the other was a list of waves.
