I once wrote a plugin (http://toolsmiths.blogspot.com/2010/04/one-bug-multiple-branches.html) to answer two related questions:
1. Which versions is this bug present in?
2. Which bugs are present in a specific version?
I created a project named Builds. Every build of the software created a Build issue in the project. Build issues were linked to the previous build and the next build. When a version control branch occurred the Build issue was linked to two next builds.
Each bug indicated the builds that it was confirmed present in (affects), and the builds that it was confirmed not present in (fixed). Then the plugin created reports to answer the two key questions by creating a tree of the Builds involved. The nice thing was that discovering a bug in some released build automatically showed the bug as affecting the latest build. This dynamic info was useful.
I'm not really sure why more bug trackers don't support multiple releases better. It's been a pain point in most places I've worked at.