If you are a Gmail user, you might already have noticed that Google added a social networking feature called 'Buzz' to Gmail. While it is definitely useful, there are some privacy concerns that you should take note of when using Buzz. I will list below what I have noticed so far. If you find anything not listed here, you can always put it in the comments.
1. All your posts and comments are public by default. You can choose to send your message to only few of your friends (check the drop-down with Public and Private options). If you comment on your friend's public post, your comment will be public too. So, be careful while posting and commenting as it is not a one-to-one chat window or email.
2. If you create a public profile (Google asks you to create one when you are sending a message using Buzz), the list of people you follow and the list of people who are following you is visible to everyone by default. If you want to keep this private, go to your profile, click on the 'Edit profile' link and uncheck the option "Display the list of people I'm following and people following me".
3. When you post a message and when somebody replies to your message in Buzz, it will be added as a mail in your Inbox. You can safely delete these mails without disturbing the message inside Buzz. To delete these mails, search by typing 'is:buzz' inside the search box. You can automate this by creating a filter.
4. If you have an iPhone or any Android phone, be careful while posting to Buzz from your mobile. It will add your current location to the message. You can choose to hide your location.
5. Google automatically adds you as a follower of your friends in Gmail contacts. Click on the 'Following 9 people' link and remove those you do not want to follow. Similarly, click on '9 followers' link to block unwanted people. And click on the '3 connected sites' link to remove sites like Picasa, if you don't like to share the link to your photos.
If you are tired of all these and think you don't need Buzz, you can just turn it off by logging into Gmail and clicking the 'turn off buzz' link at the bottom of the screen.
Happy buzzing ...