You summed it up when you said, “users already have too many islands to which they must row, in order to participate online”.
I depend on and enjoy using Gmail, G Cal and other Google apps, and I looked forward to using Wave and Buzz. I was surprised to find Buzz and Wave to be not-so-useful. I admit that I did not give either much of a try because I could not determine right away that these apps would be better than what I was already using, and I just don’t have the time to mess around with something that could work for me, but may not. I like the BuzzWave idea!