Confluence 5.7 introduced inline commenting, which is great. It would be even better if these comments could be made while editing the page.

Another thing I noticed is that when I am editing a page and at the same time add a comment (in the read mode) that does not affect the comment I have edited, when saving the page, I am prompted to override the changes, which will remove my comment. So that's another reason for having inline comments in the edit mode.