As an adult, I had issues with privacy on Google Buzz. If I had a hard time finding the information to make my profile secure, I don't think most kids are savvy enough to understand the privacy policy and set user controls to protect themselves. Horrible product from Google.
Privacy, or the lack of, make Google Buzz a definite "no" for children under the age of 13. Parents need to be aware of what their children post on the internet - especially when it comes to sharing their personal information.
I have google buzz, and I like it, there are a lot of great things about it. One thing I did want to point out though, is that is someone starts to follow you that you don't know, autimatically block them.