This is the sort of thing that was absolutely predictable.
a) The Google Buzz people are so stupid that they couldn't have predicted this absolutely predictable thing (no one else did that I know of until it bit them) or
b) they knew this would happen and chose to allow it to happen in the bad times hoping the love they'd get from those who like it would be greater than the pain experienced by those to whom it happened.
If either (a) or (b) is true, can we trust Google with our private information? Either they are too dumb to keep it out of the wrong hands or they don't care about individuals' privacy.