Shortly after Google unveiled its new social application known as "Buzz," reactions across the Web shifted from curiosity at the latest effort to rival Facebook and Twitter in the social space to deep concerns over the privacy implications of the service.

Specifically, commentators have warned that the lists of contacts Buzz assembles for Gmail users based on whom they write or chat with most frequently are made publicly available by default.

That has invited widespread hand wringing as bloggers have imagined scenarios in which bosses can snoop on employees, jealous spouses on their partners and the general creepiness that attends the idea of publishing the contents of one's inbox on the Web. Additionally, when users sign up for Buzz, Google does not explicitly state that the list of followers will be publicly available.

Google, which did not immediately respond to requests for comment for this story, has maintained that users have the ability to edit the settings to limit the visibility about their contacts, and of course a person's followers are only viewable to other Buzz users when set up through a public profile with the company.

Nevertheless, the concerns about the default public setting persist, largely because of the common tendency among casual technology users to accept default settings without giving the details a close read.

If that sounds familiar, there's a reason.

Much of the online privacy debate that has been raging since the early days of the Web surrounds user consent and how much notice companies must give users about their data policies. So often when a company -- be it Google, Facebook, or any other popular Web firm -- introduces a new product that promises a more social, personalized Internet experience, privacy advocates may view it as a sneaky ploy to trick users into sharing more personal information.

That raises the opt-in versus opt-out debate, which is expected to pick up in earnest in the coming months as House lawmakers ready a bill that is expected to contain requirements that would force Internet firms to secure explicit permission from users when collecting certain types of information.

Facebook recently came under fire for its site-wide redesign, which carried default settings that made portions of a user's profile available across the Web. A coalition of privacy advocates has petitioned the Federal Trade Commission to investigate and force Facebook to restore the previous settings.

Kenneth Corbin is an associate editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.