Redmine

Sorry for typo in summary: should be:
"Support for milestones/iterations as part of projects"

+1

A good, complete implementation of the milestones idea would
really be valuable. That was one set of features I really liked
about Mingle, which we ultimately rejected in favor of Redmine.
There, you can set up and schedule milestones, and even drag
and drop issues among milestones as priorities or schedules change.
There was a very nice "card" view, showing milestones
in chronological order with a flashcard-like appearance. This
would be fantastic for Agile shops like ours, and like the submitter
said, could enhance the Roadmap view as well as overviews, Gantt
charts, etc.

Thanks Daniel for popping up this old request.

I absolutely agree that it would make sense to have a kind of subversions, submilestones...

For software development I would normally use a "version" for a release of the software, but for development this version could be subdivided into milestones.
For every version, support for sub-versions (they may be called milestone, iteration, etc...) would help a lot.

To make this more generic, the "version" (or whatever a good generic name would be then) should have a choosable name attribute like: Version, milestone, iteration... This could even be free text.

But I think the most important part for the beginning would be to have parent child relations of versions. I think this would e.g. also help for the redmine backlogs plugin (agile) which is currently using "versions" for sprints which makes the "versions" themselves unusable for real software version handling.

Have a look at my proposal over at issue #13387, where I describe adding issues' relationship model to versions to accomplish this and more.