It's yet another new feature for Google Buzz and it looks like the Buzz team has not only learned from their own launch but from Facebook criticism as well.
A short time ago, many Buzz users were greeted with a top screen that looked like this (Note: You'll have to tap the image to enlarge it):
Note: The default is opt-in, NOT opt-out.
Despite the fact that the feature isn't completely revolutionary (Friendfeed has a similar function), Kudos go out to the team at Buzz for rolling out features slowly, allowing users time to experiment, and for making each step opt-in rather than opt-out.
More on the new Google Buzz feature can be found at the Google Buzz Team Buzz profile here.
So far, it appears those who have commented agree with me ....
I suggest you 'like' it!