When the public reaction to Google Buzz took a fast negative turn, the company made swift changes to alleviate privacy concerns surrounding the service’s automatic tendency to share information.

But now, Google may be taking an even more drastic step: One of Google’s top executives has said that the company may be splitting Buzz apart from Google, making it a standalone service that can still integrate into Gmail:

Iran has taken steps towards permanently blocking Gmail and other Google email services, the Wall Street Journal reports. The country plans to launch “a national email service for Iranian citizens” to replace it, which, it’s fair to say, will probably not give its users Tor-like anonymity and will only exacerbate dissident crackdowns. Google Buzz one-liners aside, this is chilling news.

As you’ve no doubt heard, Google signaled its move into the social media arena in a big way at 10am PST today by announcing the launch of Google Buzz, a Gmail-integrated social networking utility which will roll out over the next few days.

So: what is Google Buzz, exactly? Below, ten things that define what it is — and what it isn’t:

Google’s press conference announcing status upgrades to Gmail is soon to begin. It was scheduled for 10am PST, but CNET’s liveblog of the event reported a “few more minutes” notice. At 10:14am PST, they report “The Google Train is now starting.”

Google’s got the conference streaming on YouTube, so: check it out. We’ll continue to write about it as new stuff emerges.