(This is self-promotional, but hopefully relevant. Please downvote if you disagree.) At Leanpub we fundamentally disagree with the point of this article [that

(This is self-promotional, but hopefully relevant. Please downvote if you disagree.) At Leanpub we fundamentally disagree with the point of this article [that writers don't want their old versions], and agree with what Etherpad was going for with the time slider: we use Git for all the book revisions (both with our in-browser editor or via a direct interface to GitHub), but we do this in an unobtrusive way. (We'll probably expose a similar time slider eventually, but for git revisions.) While this may or may not be needed for writing of essay length, we feel it is essential for books. Also, imagine the contribution to scholarship if, say, Ulysses had been written with version control...