So sad to see Google throw in the towel on Google Wave.
In retrospect the obvious is pretty clear - the way to get mass wave adoption was to build a really solid bridge between SMTP, IM, and Twitter/ostatus worlds.
Yes, I know people did build those all of those connections and more but the wave team was a fairly small team and they didn't focus on making any of those Google production ready which would have led to people coming to depend on them as a primary inbox type of application.
I still think the concept of a live, read/write, communicating web world is where we are headed. Wave was definitely ahead of its time.