Like every man and his dog, I've been playing around with Google Buzz the last few days. So far it's looking quite good. It's not entirely accurate to call it a Twitter clone, but it certainly works in a very similar way.
If you'd like to have your blog posts (or other external content) posted on Twitter, you'd need to find a service that uses the Twitter API to post messages. Google Buzz works the opposite way, and Google will pull updates from other services (Twitter, Flickr, Blogs, Youtube, Google Chat, Picasa, Google Reader) and show them in your Buzz feed.
Currently, there's no built-in way to send your Buzz updates back to these services, though there are a few 3rd party services and workarounds to make this work.
DeWitt Clinton posted an interesting Buzz (?) about where Google Buzz is heading. It focuses on being open and interoperable. Rather than a closed system like Twitter, where you can only share with other Twitter users, Google are promoting an open system where different hosts can exchange messages with each other, like how other systems like Email and Google Wave work.
I have high hopes for Google Buzz. For too long have we put up with Twitter's fail whale and erratic API. It's time for their monopoly to end and everyone to play nicely together.