The admin should be able to define post tags in the ACP for specific forums and members should then be able to select a post type while replying.
Then one could just filter/highlight specific types (e.g. to see only all the bugs)

Usecase would be my downloads support topics for the small apps, where it's not really worth to have separate forums for suggestions and bugs and instead just the support topic where people should be able to leave suggestions, feedback and bug reports.

This was completed