Google Buzz is the search giant's attempt to convert its Gmail service into a social network, but it has alienated many users by mining personal information in other Google-run services to boost Buzz usage.
When it was launched last week Buzz was set to automatically use information from people's Google web mail accounts and RSS-reading Reader service in a bid to kick-start the service.
It automatically signed users up to 'follow' the Buzz activity of the people they communicated with most on Gmail and connected followers to items shared by a user through the Reader service.
The company was accused not only of violating users' privacy but of burying the mechanism to change the settings in an obscure part of the service's menus. It has twice modified the service in a bid to allay users' concerns.
Google first made the option for switching off the auto-follow more prominent, then changed it altogether so that it only suggested people a user might like to follow.
"On Thursday, after hearing that people thought the checkbox for choosing not to display this information publicly was too hard to find, we made this option more prominent," said Gmail and Buzz product manager Todd Jackson in a blog post. "But that was clearly not enough. So starting this week, instead of an auto-follow model in which Buzz automatically sets you up to follow the people you email and chat with most, we're moving to an auto-suggest model. You won't be set up to follow anyone until you have reviewed the suggestions and clicked 'Follow selected people and start using Buzz'."
Google said that it would also be severing the automatic links between Buzz and content posted by users via other Google-owned web services, Reader and photo hosting service Picasa.
Buzz faces the challenge of convincing millions of Twitter and Facebook users to use Buzz either instead of or as well as those services.
Jackson said that the connections with the other Google services were designed to populate the Buzz network quickly.
"With Google Buzz, we wanted to make the getting started experience as quick and easy as possible, so that you wouldn't have to manually peck out your social network from scratch," he said. "However, many people just wanted to check out Buzz and see if it would be useful to them, and were not happy that they were already set up to follow people. This created a great deal of concern."
The fact that followers were decided on based on the amount of communication Gmail users had with certain contacts could put some users in real danger, according to diplomacy academic Evgeny Morozov of Georgetown University in the US.
"I am extremely concerned about hundreds of activists in authoritarian countries who would never want to reveal a list of their interlocutors to the outside world," he said in a blog post. "Why so much secrecy? Simply because many of their contacts are other activists and often even various 'democracy promoters' from Western governments and foundations. Many of those contacts would now inadvertently be made public."
"If I were working for the Iranian or the Chinese government, I would immediately dispatch my Internet geek squads to check on Google Buzz accounts for political activists and see if they have any connections that were previously unknown to the government. They can then spend months on end drawing complex social circles on the shiny blackboards inside secret police headquarters," he said.
Google's Jackson acknowledged that the company had made mistakes. "We quickly realized that we didn't get everything quite right," he said. "We're very sorry for the concern we've caused and have been working hard ever since to improve things based on your feedback. We'll continue to do so."