What does this feature do?
It would be a nice to have feature to allow a way for tickets to be related to one another.
This could be as simple as having a "related ticket" options; but it could be expanded further to include the type of relationship - the predominant one being dependent ticket / prerequisite ticket style relationship.
What makes this feature interesting?
This feature would help with the grouping of tickets at a more granular level than Milestones.
On larger projects, or projects with many developers, it would allow for efficient delegation of tickets based on dependency chains within a targeted release point.