The Buzz screw up was in a whole different league to the usual privacy fail. "Normally" they revolve around accidentally (or not) leaking some bit of data to a bunch of other people you have indicated you want to share some data with (by "friending" them or some other mechanism).

The Buzz was something else indeed. It was taking some people you had had contact with for random reasons, i.e. you had had email conversations with them and suddenly giving them access to a bunch of data that, where you had no intention to let them have any data.

And worse than that, withdrawing from Buzz did not deny them access to that data.