Thanks Dale for all the explanations. How Monticello and version control relate in the big picture is starting to make sense for me.
Now, I better understand why filetree ended up uses a file-per-method format, even though that is relatively hostile to git user interfaces optimised for other languages. There is really a need for a file-per-class exchange format, because that would works a lot better with the existing VCS ecosystem. I think more package-based user interfaces would indeed be a very good idea, for browsing and for source code management. Stef, I have the impression you think that git is popular because it is a new shiny toy. I disagree with this idea. Git is a typical worse-is-better tool. It's good enough for most people, but it still has many shortcomings. It is popular in spite of its shortcomings. It became popular as destination for projects shifting from CVS and Subversion. So it is unlikely to be displaced by a newer, incrementally shinier tools. Anything that will displace it will have to provide an improvement of a similar magnitude as the jump between centralised and distributed version control. Still, I think it's a good idea not to restrict high level models to what git provides if that's a less than ideal fit to the image model. I have a lot of ideas to improve browsing and source code management in Pharo. I can make no promises, but I would like to produce something there.
