Google Buzz brings status updates, links, videos and other shared features into the Gmail interface. If you've updated through Facebook or Twitter you'll be comfortable with the process: enter a quick sentence or paragraph describing ... well, anything really. Your thoughts. A recommended link. A question. It's all fair game.
1. How does Google Buzz work?
Google Buzz appears as an option in you Gmail navigation (you may not see it yet because it's being rolled out in waves). Buzz uses the people you email and chat with most often to build the first iteration of your network. You can add and prune from there.
You can choose to share Buzz updates publicly or privately on a post-by-post basis (more on that below).
Looks interesting - it's aggregating things together rather than building a whole new ecosystem. But by doing so, they're creating another method to create/consume social media. And by adding it directly to Gmail they have an automatic audience - rather than another new site you have to go to that is separate.
There's lots of startups in this space, but they never had the built in advantage that Google had with Gmail.