I was a heavy user of Wave for the brief period of time it existed. Although I struggle to think of how I will integrate this into my workflow today, I am excited to give it a try.
Wave was perfect for summer specific processes, like development of a tech specifications or making a complex contracts. Collapsing branches were much more usable than comments in Google Docs: you can't have a lengthy discussion in Docs, but in Wave it was natural.
Still, the team has to be disciplined, or else Wave quickly became chaotic.