post-revision module available in 3.1 – display problem

In a hosted stock wp 3.1 with Weaver 1.5.4 I am attempting to view revisions of a post.
In this article https://en.support.wordpress.com/posts/post-revisions/
I see what I thought I have seen before. It occurs to me that perhaps this feature as described is only available to a wordpress.com blog?

I would like to have this functionality in my self hosted wp 3.1 blog. Is it supported in wordpress 3.1 distribution?

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Eventually I would like users to be able to do a diff on versions of a post and allow comments to be made. For instance on chapters of a book, a newsletter or poem.