Google's new social networking service, Buzz has upset a lot of people who have inadvertently posted the list of the people they email and chat with most frequently on their profile. If you took the default options and didn't opt-out or edit this list during profile creation, the list becomes part of your profile. Since who you email with frequently can often be private information (reporters and sources, doctors and patients, former significant others, etc), making this list public can create serious problems.
If you're going to use Google Buzz, we recommend that you opt-out during profile creation. If you have already created a profile, change it to private immediately. Then go through the suggested list, and edit it as appropriate before making it public again. PC World has a helpful privacy checklist to help users understand the privacy implications of Google Buzz options.
Google has attempted to address some of these issues, making it easier to block people and hide the friend list. The underlying issue is that your email and chat contacts are not necessarily people you want to advertise as friends via a public social network. Since Google's competitors make it hard to transfer list of social contacts to new services, Google attempted to jump start Buzz with lists drawn from its successful Gmail and Gchat services. While this may help Buzz grow and save users the time to type in all their contacts, it also has an inherent danger of inadvertent disclosure of private information. Google could significantly reduce this problem simply by making the list private by default, so users could opt-in after reviewing the suggested list.
Google might also consider allowing those who agreed to join Google Buzz without understanding its implications to opt-out fully. Currently, "turning off" Google Buzz merely suspends the viewing and public broadcasting of messages until you might want to re-connect your private email world and the public space again. Some Gmail users would prefer that those worlds stay strongly unconnected. They do not want a list of potential "followers" to gather, awaiting the moment that a user mistake or poor interface design inadvertently reveals private data to the world once again. Google is apparently considering separating Buzz from Gmail.