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Do you mean with circles?
More or less. I think the stream is a good way of presenting stories, like this:
http://i.imgur.com/5ocCv.png Clicking on an item brings up comments, and lets you add your own, like this: http://i.imgur.com/mhAfy.png It doesn't have the power of threaded comments, but neither do FB or twitter. It is, however, easy to use and pleasant looking.