An interesting feature of Google's Buzz is that it updates messages. I have it set up so that every blog post I create becomes a Buzz message. That's fine, but not all that unusual. What's especially neat is that when I edit my blog post, the Buzz message is edited at well.
So I guess this means that the Buzz messages aren't copied from the blog and sent as messages. What Buzz must send as messages to its message stream are pointers back to the blog entries so that when you look at a Buzz entry that pointer is expanded to show the current content of the blog entry. Very neat.