Another interesting article from Mashable. On the reason of the quick spread of the Google Buzz service I strongly agree with this point:
Daniel L – The main reason buzz is growing so quickly is because it is easily accessible to Gmail’s large and already established user base. Normally, Gmail is the one site i always have open because it has my calendar, my to do list, and my chat all in one window. Because of this, i always see when i have new Buzz, and i will tend to check it and respond. This is the #1 reason i use it — convenience.
and believe that this shows how pervasive is Google in our life and the level of “trust” and “loyalty” it has reached on people. I strongly doubt that any other service would have survived the first couple of days privacy issues that have manifested.