At Freelock, we've been adopting a pattern for git branch management called Git Flow. If you haven't run across git flow before, go check out this article to get the basic concepts: A successful Git branching model.
At Freelock our project management tool of choice is Open Atrium.
OpenAtrium is an online collaboration and task-management suite built on top of Drupal. Like Drupal, it is completely modular, so the feature set can be changed and expanded to meet the needs of a wide variety of applications. Out of the box it has support for case management, collaborative document editing, shared blog and microblog, and a variety of user-configurable dashboard views.