We need to admit, these days, people are more reliant on contributed modules then Drupal core. What is in Drupal core is taken as a given and some requested new feature would ever come in a contributed module in a reasonable timeframe for a Drupal site builder. People are not waiting for Drupal 7 to get a feature, people are active in the issue queues to get things done sooner. Drupal core is supposed to lay the foundation and be stable for long, while contributed modules can experiment, change, and add new features on a much more active pace. So as a result, Drupal core can keep using the "will be released sometime" approach, and it does well with Drupal 7 allowing for more improvements by not keeping the "every 12 months" release cycle intact. With contributed modules on the other hand, much more frequent releases are anticipated with new features introduced through a shorter timeframe.
What's common in both, is that for longer lasting development, overseeing progress on major areas like the file API, the database layer and so on is important, while on shorter release cycles, knowing what is required for the release to be fixed, and whether the project is on track or not could be key to get contributors. So having (A) overviews of project progress and (B) checklists of things to be done is increasingly needed on drupal.org. There are a few things people did about these needs recently, and all have their advantages and disadvantages. There are some reasonably new approaches, so I decided to highlight the ways I see people approach project planning on drupal.org.
Drupal.org runs the infamous project* module family to help micro (and not so micro) projects run around the Drupal core. These include modules, themes and translations as well as installation profiles. Currently, drupal.org hosts more then four thousand (yes, more then 4000) projects, with support for a CVS space for hosting the code with branching and tagging, as well as a release system tied to those CVS concepts. Projects can also have an issue queue, which people can submit issues with, covering bug fix requests and suggestions as well as new feature requests. So a project's issue queue can be quite busy, but it is the only "core" way to track what needs to be done, who is assigned to these tasks, who is working on them, what is the current status and so on.
So eventually people started to experiment building new tools on top of project issues to help manage project planning, overviews and checklists. Here is a hopefully comprehensive list of what tools people built on top: