Google Buzz just got a new feature that is very similar to Twitter's retweet functionality. Over the course of the day, Google will roll out a Reshare button for Buzz, which will allow you to easily share interesting posts you find on Buzz with your followers there.
These posts can be shared both publicly and privately. According to Google, this was one of the top user requests for Buzz. It is also a good example of the incremental updates the Buzz team has made over the last three months.