If you prefer a descending order (like in changelogs, blogs, etc.) for milestones in roadmaps instead of an ascending one (= default), you might want to apply my tiny patch:
It applies to Roadmap.py of Trac 0.8.4 (see ‘locate Roadmap.py’).
Note that this patch both sets a reverse chronological and a reverse alphabetical order for milestones. Like this, you can name your milestones like versions (e.g. “0.2”, “0.4” .. “1.0”) and they will still appear in reverse order (even if they don’t have any associated dates).
If you want a reverse chronological only order (while keeping an ascending alphabetical order), set “name” instead of “name DESC” in the SQL statements of Roadmap.py.
Note that iCal will not be affected by the display order of the items on Trac.