It sure would be nice to be able to add a comment at the same time as editing a page, like in JIRA. It should link to the "View diffs to previous version" page. This way you could say "just added new section Xxxx", etc, and most people wouldn't have to spend time looking at the Version History page.

The version history page should have the option of showing the change-comments inline too, so you can find the old version you want without having to click on and read many diffs.