Why Wave Failed
Florian Wardell submitted a little discussion piece about Why Wave Failed. He blames marketing and the staged rollout. Personally I think that what killed it was that I should have transparently been able to see my gmail inside wave. Requiring a separate window guarantees that I wouldn't use it regularly. Had I been able to read my regular mail in the same UI, I might have been tempted to use it more.
So, what is "Wave"? Oh, I see...
Everything you know is wrong, Just forget the words and sing along.