According to Computerworld, the Electronic Privacy Information Center has filed a complaint with the U.S. Federal Trade Commission claiming that Google Buzz violates user privacy.
EPIC wants the FTC to investigate Google and force it to change or stop offering several features of Buzz. Google has already made changes to Buzz's privacy settings following user complaints.
Specifically, EPIC is unhappy that Gmail users are automatically signed up to be part of Buzz unless they uncheck a box. It also doesn't like that Google uses Gmail users' address books to create Buzz user follower lists:
An attempt by an email service provider to attempt to convert the personal information of all of its customers into a separate service raises far-reaching concerns for subscribers and implicates both consumer and personal privacy interests.