A dedicated wiki page for “Changelog” or “Version History” is needed and should/could be linked from Main Page, Download page (next to version number) and on release announcements on Blog or mailing lists.
Additional work could be combining and simplifying the old and upcoming changelogs to be relevant to average users or better, having two type of changelogs, “simple, short, major changes” and “long, advanced, all changes”. Simple one should be linked from main page, download page and release announcements. The advanced log could be linked from inside this simple changelog, preferably linking from next to each version.
The simple changelog could include additional short descriptions as to how the changes are useful for users as well as having a focus on most important topics like anonymity, security, visual changes, functional changes, usability changes etc.