http://belaus.com.au/2008/03/07/redmine/

The nitty gritty:

• Requirements / Use Cases
• versioned documents tied to releases
• document diff
• Generate Word / RTF / PDF
• auto generate “requirements for release”
• description of what’s deployed in different environments (qa/uat/prod)

and from the comments

• ability to decompose a requirement into parts
• assign parts of a requirement to different iterations / releases
• define iteration length and schedule == roadmap
• break down use cases into scenarios (and assoc to release)