GMAIL USERS: You’re invited to join the conversation on Mashable’s Google Buzz account.

GoogleGoogle Buzz just launched on Tuesday, but it looks like it’s already made a big splash with GmailGmail users. Now the Google team is moving quickly to make rapid improvements based on user feedback.

First the numbers: According to Google, its Buzz service already has more than nine million posts and comments. Remember, this is a service that launched on Tuesday, meaning that it’s getting more than 160,000 comments and posts per hour. That’s a staggering, staggering number.

Mobile usage is also gaining in popularity — more than 200 posts per minute by mobile phone according to the search giant.

Despite those numbers, there have been a number of complaints about Google BuzzGoogle Buzz in terms of usability and privacy. In rather rapid fashion, Google has responded to those criticism in a blog post highlighting several new changes it has made.

Specifically, there are three new changes to Google Buzz:

1. It’s now easier to hide your followers/following lists. The option is now more visible in the set-up process and exists in the profile editing section of Buzz.

2. It’s easier now to block anybody who is following you. Before, you could only block people who created a public profile.

3. Buzz now distinguishes between followers with public profiles and those with private profiles.

These changes came quite rapidly, and we’re thrilled that they’re now more prominent parts of Google Buzz. They were major concerns that the company needed to alleviate. We just didn’t think they would be able to do it in two days.